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 Title
 Absence Of Dirac States In Baznbi2 Induced By Spinorbit Coupling.
 Creator

Ren, Weijun, Wang, Aifeng, Graf, D., Liu, Yu, Zhang, Zhidong, Yin, WeiGuo, Petrovic, C.
 Abstract/Description

We report magnetotransport properties of BaZnBi2 single crystals. Whereas electronic structure features Dirac states, such states are removed from the Fermi level by spinorbit coupling (SOC) and consequently electronic transport is dominated by the small hole and electron pockets. Our results are consistent with not only threedimensional, but also with quasitwodimensional portions of the Fermi surface. The SOCinduced gap in Dirac states is much larger when compared to isostructural...
Show moreWe report magnetotransport properties of BaZnBi2 single crystals. Whereas electronic structure features Dirac states, such states are removed from the Fermi level by spinorbit coupling (SOC) and consequently electronic transport is dominated by the small hole and electron pockets. Our results are consistent with not only threedimensional, but also with quasitwodimensional portions of the Fermi surface. The SOCinduced gap in Dirac states is much larger when compared to isostructural SrMnBi2. This suggests that not only longrange magnetic order, but also mass of the alkalineearth atoms A in ABX(2) (A = alkalineearth, B = transitionmetal, and X = Bi/Sb) are important for the presence of lowenergy states obeying the relativistic Dirac equation at the Fermi surface.
Show less  Date Issued
 20180122
 Identifier
 FSU_libsubv1_wos_000423341500001, 10.1103/PhysRevB.97.035147
 Format
 Citation
 Title
 Acoustic wave absorption as a probe of dynamical geometrical response of fractional quantum Hall liquids.
 Creator

Yang, Kun
 Abstract/Description

We show that an acoustic crystalline wave gives rise to an effect similar to that of a gravitational wave to an electron gas. Applying this idea to a twodimensional electron gas in the fractional quantum Hall regime, this allows for experimental study of its intraLandau level dynamical response in the longwavelength limit. To study such response we generalize Haldane's geometrical description of fractional quantum Hall states to situations where the external metric is time dependent. We...
Show moreWe show that an acoustic crystalline wave gives rise to an effect similar to that of a gravitational wave to an electron gas. Applying this idea to a twodimensional electron gas in the fractional quantum Hall regime, this allows for experimental study of its intraLandau level dynamical response in the longwavelength limit. To study such response we generalize Haldane's geometrical description of fractional quantum Hall states to situations where the external metric is time dependent. We show that such timedependent metric (generated by acoustic wave) couples to collective modes of the system, including a quadrapolar mode at long wavelength, and magnetoroton at finite wavelength. Energies of these modes can be revealed in spectroscopic measurements, controlled by straininduced Fermi velocity anisotropy. We argue that such geometrical probe provides a potentially highly useful alternative probe of quantum Hall liquids, in addition to the usual electromagnetic response.
Show less  Date Issued
 20160415
 Identifier
 FSU_libsubv1_wos_000374297500001, 10.1103/PhysRevB.93.161302
 Format
 Citation
 Title
 Anisotropic Antiferromagnetic Order In The Spinorbit Coupled Trigonallattice Ca2sr2iro6.
 Creator

Sheng, Jieming, Ye, Feng, Hoffmann, Christina, Cooper, Valentino R., Okamoto, Satoshi, Terzic, Jasminka, Zheng, Hao, Zhao, Hengdi, Cao, G.
 Abstract/Description

We used singlecrystal xray and neutron diffraction to investigate the crystal and magnetic structures of trigonal lattice iridate Ca2Sr2IrO6. The crystal structure is determined to be R (3) over bar with two distinct Ir sites. The system exhibits longrange antiferromagnetic order below TN = 13.1 K. The magnetic wave vector is identified as (0,0.5,1) with ferromagnetic coupling along the a axis and antiferromagnetic correlation along the b axis. Spins align dominantly within the basal...
Show moreWe used singlecrystal xray and neutron diffraction to investigate the crystal and magnetic structures of trigonal lattice iridate Ca2Sr2IrO6. The crystal structure is determined to be R (3) over bar with two distinct Ir sites. The system exhibits longrange antiferromagnetic order below TN = 13.1 K. The magnetic wave vector is identified as (0,0.5,1) with ferromagnetic coupling along the a axis and antiferromagnetic correlation along the b axis. Spins align dominantly within the basal plane along the [1,2,0] direction and tilt 34 degrees toward the c axis. The ordered moment is 0.66(3) mu(B) /Tr, larger than other iridates where iridium ions form corner or edgesharing IrO6 octahedral networks. The tilting angle is reduced to approximate to 19 degrees when a magnetic field of 4.9 T is applied along the c axis. Density functional theory calculations confirm that the experimentally determined magnetic configuration is the most probable ground state with an insulating gap similar to 0.5 eV.
Show less  Date Issued
 20180611
 Identifier
 FSU_libsubv1_wos_000434761900004, 10.1103/PhysRevB.97.235116
 Format
 Citation
 Title
 Changes in the electronic structure and spin dynamics across the metalinsulator transition in La1xSrxCoO3.
 Creator

Smith, R. X., Hoch, M. J. R., Moulton, W. G., Kuhns, P. L., Reyes, A. P., Boebinger, G. S., Zheng, H., Mitchell, J. F.
 Abstract/Description

The magnetoelectronic properties of La1xSrxCoO3, which include giant magnetoresistance, are strongly dependent on the level of hole doping. The system evolves, with increasing x, from a spin glass insulator to a metallic ferromagnet with a metalinsulator (MI) transition at x(C) similar to 0.18. Nanoscale phase separation occurs in the insulating phase and persists, to some extent, into the justmetallic phase. The present experiments at 4.2 K have used La139 nuclear magnetic resonance to...
Show moreThe magnetoelectronic properties of La1xSrxCoO3, which include giant magnetoresistance, are strongly dependent on the level of hole doping. The system evolves, with increasing x, from a spin glass insulator to a metallic ferromagnet with a metalinsulator (MI) transition at x(C) similar to 0.18. Nanoscale phase separation occurs in the insulating phase and persists, to some extent, into the justmetallic phase. The present experiments at 4.2 K have used La139 nuclear magnetic resonance to investigate the transition from hopping dynamics for x < x(C) to Korringalike ferromagnetic metal behavior for x > x(C). A marked decrease in the spinlattice relaxation rate is found in the vicinity of x(C) as the MI transition is crossed. This behavior is accounted for in terms of the evolution of the electronic structure and dynamics with cluster size.
Show less  Date Issued
 20160125
 Identifier
 FSU_libsubv1_wos_000369218500003, 10.1103/PhysRevB.93.024204
 Format
 Citation
 Title
 Charge avalanches and depinning in the Coulomb glass: The role of longrange interactions.
 Creator

Andresen, Juan Carlos, Pramudya, Yohanes, Katzgraber, Helmut G., Thomas, Creighton K., Zimanyi, Gergely T., Dobrosavljevic, V.
 Abstract/Description

We explore the stability of farfromequilibrium metastable states of a threedimensional Coulomb glass at zero temperature by studying charge avalanches triggered by a slowly varying external electric field. Surprisingly, we identify a sharply defined dynamical ("depinning") phase transition from stationary to nonstationary charge displacement at a critical value of the external electric field. Using particleconserving dynamics, scalefree systemspanning avalanches are observed only at the...
Show moreWe explore the stability of farfromequilibrium metastable states of a threedimensional Coulomb glass at zero temperature by studying charge avalanches triggered by a slowly varying external electric field. Surprisingly, we identify a sharply defined dynamical ("depinning") phase transition from stationary to nonstationary charge displacement at a critical value of the external electric field. Using particleconserving dynamics, scalefree systemspanning avalanches are observed only at the critical field. We show that the qualitative features of this depinning transition are completely different for an equivalent shortrange model, highlighting the key importance of longrange interactions for nonequilibrium dynamics of Coulomb glasses.
Show less  Date Issued
 20160324
 Identifier
 FSU_libsubv1_wos_000372712000002, 10.1103/PhysRevB.93.094429
 Format
 Citation
 Title
 Chiral spin liquid from magnetic Wannier states.
 Creator

Panfilov, I., Patri, A., Yang, Kun, Burkov, A. A.
 Abstract/Description

We present a mapping of a twodimensional system of interacting bosons in a strong perpendicular magnetic field to an equivalent system of interacting bosons on the square lattice in the absence of the field. The mapping utilizes a magnetic Bloch and the corresponding magnetic Wannier singleparticle basis in the lowest Landau level. By construction, the ground states of the resulting model of interacting bosons on the square lattice are gapped fractionalized liquids or gapless Bose metal...
Show moreWe present a mapping of a twodimensional system of interacting bosons in a strong perpendicular magnetic field to an equivalent system of interacting bosons on the square lattice in the absence of the field. The mapping utilizes a magnetic Bloch and the corresponding magnetic Wannier singleparticle basis in the lowest Landau level. By construction, the ground states of the resulting model of interacting bosons on the square lattice are gapped fractionalized liquids or gapless Bose metal states with broken timereversal symmetry at specific rational filling fractions.
Show less  Date Issued
 20160316
 Identifier
 FSU_libsubv1_wos_000372413000006, 10.1103/PhysRevB.93.125126
 Format
 Citation
 Title
 Classification Of Symmetry Derived Pairing At The M Point In Fese.
 Creator

Eugenio, P. Myles, Vafek, Oskar
 Abstract/Description

Using the constraints imposed by the crystalline symmetry of FeSe and the experimentally observed phenomenology, we analyze the possible pairing symmetry of the superconducting order parameter focusing on intercalated and monolayer FeSe compounds. Such analysis leads to three possible pairing symmetry statess wave, d wave, and helical p wave. Despite the differences in the pairing symmetry, each of these states is fully gapped with gap minimum centered above the normal state Fermi surface,...
Show moreUsing the constraints imposed by the crystalline symmetry of FeSe and the experimentally observed phenomenology, we analyze the possible pairing symmetry of the superconducting order parameter focusing on intercalated and monolayer FeSe compounds. Such analysis leads to three possible pairing symmetry statess wave, d wave, and helical p wave. Despite the differences in the pairing symmetry, each of these states is fully gapped with gap minimum centered above the normal state Fermi surface, in agreement with photoemission data of Zhang et al. [Phys. Rev. Lett. 117, 117001 (2016)]. The analysis provides additional insights into the possible pairing mechanism for each of these states, highlighting the detrimental role of the renormalized repulsive intraorbital Hubbard U and interorbital U' and the beneficial role of the pair hopping J' and the Hund's J terms, as well as the spinorbit coupling in the effective lowenergy Hamiltonian.
Show less  Date Issued
 20180706
 Identifier
 FSU_libsubv1_wos_000437735000001, 10.1103/PhysRevB.98.014503
 Format
 Citation
 Title
 Coas: The Line Of 3d Demarcation.
 Creator

Campbell, Daniel J., Wang, Limin, Eckberg, Chris, Graf, Dave, Hodovanets, Halyna, Paglione, Johnpierre
 Abstract/Description

Transition metalpnictide compounds have received attention for their tendency to combine magnetism and unconventional superconductivity. Binary CoAs lies on the border of paramagnetism and the more complex behavior seen in isostructural CrAs, MnP, FeAs, and FeP. Here we report the properties of CoAs single crystals grown with two distinct techniques along with density functional theory calculations of its electronic structure and magnetic ground state. While all indications are that CoAs is...
Show moreTransition metalpnictide compounds have received attention for their tendency to combine magnetism and unconventional superconductivity. Binary CoAs lies on the border of paramagnetism and the more complex behavior seen in isostructural CrAs, MnP, FeAs, and FeP. Here we report the properties of CoAs single crystals grown with two distinct techniques along with density functional theory calculations of its electronic structure and magnetic ground state. While all indications are that CoAs is paramagnetic, both experiment and theory suggest proximity to a ferromagnetic instability. Quantum oscillations are seen in torque measurements up to 31.5 T and support the calculated paramagnetic Fermiology.
Show less  Date Issued
 20180510
 Identifier
 FSU_libsubv1_wos_000432031700002, 10.1103/PhysRevB.97.174410
 Format
 Citation
 Title
 Coexistence of Weyl physics and planar defects in the semimetals TaP and TaAs.
 Creator

Besara, T., Rhodes, D. A., Chen, K.W., Das, S., Zhang, Q. R., Sun, J., Zeng, B., Xin, Y., Balicas, L., Baumbach, R. E., Manousakis, E., Singh, D. J., Siegrist, T.
 Abstract/Description

We report a structural study of the Weyl semimetals TaAs and TaP, utilizing diffraction and imaging techniques, where we show that they contain a high density of defects, leading to nonstoichiometric single crystals of both semimetals. Despite the observed defects and nonstoichiometry on samples grown using techniques already reported in the literature, de Haasvan Alphen measurements on TaP reveal quantum oscillations and a high carrier mobility, an indication that the crystals are of...
Show moreWe report a structural study of the Weyl semimetals TaAs and TaP, utilizing diffraction and imaging techniques, where we show that they contain a high density of defects, leading to nonstoichiometric single crystals of both semimetals. Despite the observed defects and nonstoichiometry on samples grown using techniques already reported in the literature, de Haasvan Alphen measurements on TaP reveal quantum oscillations and a high carrier mobility, an indication that the crystals are of quality comparable to those reported elsewhere. Electronic structure calculations on TaAs reveal that the position of the Weyl points relative to the Fermi level shift with the introduction of vacancies and stacking faults. In the case of vacancies the Fermi surface becomes considerably altered, while the effect of stacking faults on the electronic structure is to allow the Weyl pockets to remain close to the Fermi surface. The observation of quantum oscillations in a nonstoichiometric crystal and the persistence of Weyl fermion pockets near the Fermi surface in a crystal with stacking faults point to the robustness of these quantum phenomena in these materials.
Show less  Date Issued
 20160627
 Identifier
 FSU_libsubv1_wos_000378816000007, 10.1103/PhysRevB.93.245152
 Format
 Citation
 Title
 Coulombinteraction Induced Coupling Of Landau Levels In Intrinsic And Modulationdoped Quantum Wells.
 Creator

Paul, J., Stevens, C. E., Zhang, H., Dey, P., McGinty, D., McGill, S. A., Smith, R. P., Reno, J. L., Turkowski, V., Perakis, I. E., Hilton, D. J., Karaiskaj, D.
 Abstract/Description

We have performed two dimensional Fourier transform spectroscopy on intrinsic and modulation doped quantum wells in external magnetic fields up to 10 T. In the undoped sample, the strong Coulomb interactions and the increasing separations of the electron and hole charge distributions with increasing magnetic fields lead to a nontrivial inplane dispersion of the magnetoexcitons. Thus, the discrete and degenerate Landau levels are coupled to a continuum. The signature of this continuum is...
Show moreWe have performed two dimensional Fourier transform spectroscopy on intrinsic and modulation doped quantum wells in external magnetic fields up to 10 T. In the undoped sample, the strong Coulomb interactions and the increasing separations of the electron and hole charge distributions with increasing magnetic fields lead to a nontrivial inplane dispersion of the magnetoexcitons. Thus, the discrete and degenerate Landau levels are coupled to a continuum. The signature of this continuum is the emergence of elongated spectral line shapes at the Landau level energies, which are exposed by the multidimensional nature of our technique. Surprisingly, the elongation of the peaks is completely absent in the lowest Landau level spectra obtained from the modulation doped quantum well at high fields.
Show less  Date Issued
 20170628
 Identifier
 FSU_libsubv1_wos_000404469700004, 10.1103/PhysRevB.95.245314
 Format
 Citation
 Title
 Critical Filling Factor For The Formation Of A Quantum Wigner Crystal Screened By A Nearby Layer.
 Creator

Deng, H., Engel, L. W., Pfeiffer, L. N., West, K. W., Baldwin, K. W., Shayegan, M.
 Abstract/Description

One of the most fascinating ground states of an interacting electron system is the socalled Wigner crystal where the electrons, in order to minimize their repulsive Coulomb energy, form an ordered array. Here, we report measurements of the critical filling factor (nu(c)) below which a magneticfieldinduced, quantum Wigner crystal forms in a dilute, twodimensional electron layer when a second, highdensity electron layer is present in close proximity. The data reveal that the Wigner crystal...
Show moreOne of the most fascinating ground states of an interacting electron system is the socalled Wigner crystal where the electrons, in order to minimize their repulsive Coulomb energy, form an ordered array. Here, we report measurements of the critical filling factor (nu(c)) below which a magneticfieldinduced, quantum Wigner crystal forms in a dilute, twodimensional electron layer when a second, highdensity electron layer is present in close proximity. The data reveal that the Wigner crystal forms at a significantly smaller nu(c) compared to the nu(c) (similar or equal to 0.20) in singlelayer twodimensional electron systems. The measured nu(c) exhibits a strong dependence on the interlayer distance, reflecting the interaction and screening from the adjacent, highdensity layer.
Show less  Date Issued
 20180816
 Identifier
 FSU_libsubv1_wos_000441857700001, 10.1103/PhysRevB.98.081111
 Format
 Citation
 Title
 Crystal Structure And Partial Isinglike Magnetic Ordering Of Orthorhombic Dy2tio5.
 Creator

Shamblin, Jacob, Calder, Stuart, Dun, Zhiling, Lee, Minseong, Choi, Eun Sang, Neuefeind, Joerg, Zhou, Haidong, Lang, Maik
 Abstract/Description

The structure andmagnetic properties of orthorhombic Dy2TiO5 have been investigated using xray diffraction, neutron diffraction, and alternating current (ac)/direct current (dc) magnetic susceptibility measurements. We report a continuous structural distortion below 100 K characterized by negative thermal expansion in the [0 1 0] direction. Neutron diffraction and magnetic susceptibility measurements revealed that twodimensional (2D) magnetic ordering begins at 3.1 K, which is followed by a...
Show moreThe structure andmagnetic properties of orthorhombic Dy2TiO5 have been investigated using xray diffraction, neutron diffraction, and alternating current (ac)/direct current (dc) magnetic susceptibility measurements. We report a continuous structural distortion below 100 K characterized by negative thermal expansion in the [0 1 0] direction. Neutron diffraction and magnetic susceptibility measurements revealed that twodimensional (2D) magnetic ordering begins at 3.1 K, which is followed by a threedimensional magnetic transition at 1.7 K. The magnetic structure has been solved through a representational analysis approach and can be indexed with the propagation vector k = [0 1/2 0]. The spin structure corresponds to a coplanar model of interwoven 2D "sheets" extending in the [0 1 0] direction. The local crystal field is different for each Dy3+ ion (Dy1 and Dy2), one of which possesses strong uniaxial symmetry indicative of Isinglike magnetic ordering. Consequently, two succeeding transitions under magnetic field are observed in the ac susceptibility, which are associated with flipping each Dy3+ spin independently.
Show less  Date Issued
 20160712
 Identifier
 FSU_libsubv1_wos_000379500900004, 10.1103/PhysRevB.94.024413
 Format
 Citation
 Title
 Cyclotron decay time of a twodimensional electron gas from 0.4 to 100 K.
 Creator

Curtis, Jeremy A., Tokumoto, Takahisa, Hatke, A. T., Cherian, Judy G., Reno, John L., McGill, Stephen A., Karaiskaj, Denis, Hilton, David J.
 Abstract/Description

We have studied the cyclotron decay time of a Landauquantized twodimensional electron gas as a function of temperature (0.4100 K) at a fixed magnetic field (+/ 1.25 T) using terahertz timedomain spectroscopy in a gallium arsenide quantum well with a mobility of mu(dc) = 3.6 x 10(6) cm(2) V1 s(1) and a carrier concentration of n(s) = 2 x 10(11) cm(2). We find a cyclotron decay time that is limited by superradiant decay of the cyclotron ensemble and a temperature dependence that may...
Show moreWe have studied the cyclotron decay time of a Landauquantized twodimensional electron gas as a function of temperature (0.4100 K) at a fixed magnetic field (+/ 1.25 T) using terahertz timedomain spectroscopy in a gallium arsenide quantum well with a mobility of mu(dc) = 3.6 x 10(6) cm(2) V1 s(1) and a carrier concentration of n(s) = 2 x 10(11) cm(2). We find a cyclotron decay time that is limited by superradiant decay of the cyclotron ensemble and a temperature dependence that may result from both dissipative processes as well as a decrease in n(s) below 1.5K. Shubnikovde Haas characterization determines a quantum lifetime, tau(q) = 1.1 ps, which is significantly faster than the corresponding dephasing time, tau(s) = 66.4 ps, in our cyclotron data. This is consistent with smallangle scattering as the dominant contribution in this sample, where scattering angles below theta <= 13 degrees. do not efficiently contribute to dephasing. Above 50 K, the cyclotron oscillations show a strong reduction in both the oscillation amplitude and lifetime that result from polar optical phonon scattering.
Show less  Date Issued
 20160429
 Identifier
 FSU_libsubv1_wos_000375202600004, 10.1103/PhysRevB.93.155437
 Format
 Citation
 Title
 Decoherence In Semiconductor Nanostructures With Typeii Band Alignment: Alloptical Measurements Using Aharonovbohm Excitons.
 Creator

Kuskovsky, I. L., Mourokh, L. G., Roy, B., Ji, H., Dhomkar, S., Ludwig, J., Smirnov, D., Tamargo, M. C.
 Abstract/Description

We examine the temperature dependence of the visibility of the excitonic AharonovBohm peak in typeII quantum dots. We obtain a functional temperature dependence that is similar to that determined by transport experiments, namely, with the T1 term due to electronelectron collisions and the T3 term due to electronphonon interactions. However, the magnitude of the latter term is much smaller than that for the transport electrons and similar to the interaction strength of the excitonphonon...
Show moreWe examine the temperature dependence of the visibility of the excitonic AharonovBohm peak in typeII quantum dots. We obtain a functional temperature dependence that is similar to that determined by transport experiments, namely, with the T1 term due to electronelectron collisions and the T3 term due to electronphonon interactions. However, the magnitude of the latter term is much smaller than that for the transport electrons and similar to the interaction strength of the excitonphonon coupling. Such suppressed electronphonon interaction ushers a way for alloptical studies of decoherence processes in semiconductor nanostructures as other dephasing mechanisms become more pronounced.
Show less  Date Issued
 20170426
 Identifier
 FSU_libsubv1_wos_000400064400006, 10.1103/PhysRevB.95.165445
 Format
 Citation
 Title
 Detailed Study Of The Fermi Surfaces Of The Typeii Dirac Semimetallic Candidates Xte2 (x=pd,pt).
 Creator

Zheng, W., Schonemann, R., Aryal, N., Zhou, Q., Rhodes, D., Chiu, Y.C., Chen, K.W., Kampert, E., Foerster, T., Martin, T. J., McCandless, G. T., Chan, J. Y., Manousakis, E.,...
Show moreZheng, W., Schonemann, R., Aryal, N., Zhou, Q., Rhodes, D., Chiu, Y.C., Chen, K.W., Kampert, E., Foerster, T., Martin, T. J., McCandless, G. T., Chan, J. Y., Manousakis, E., Balicas, L.
Show less  Abstract/Description

We present a detailed quantum oscillatory study on the Dirac typeII semimetallic candidates PdTe2 and PtTe2 via the temperature and the angular dependence of the de Haasvan Alphen and Shubnikovde Haas effects. In highquality single crystals of both compounds, i.e., displaying carrier mobilities between 10(3) and 10(4) cm(2)/Vs, we observed a large nonsaturating magnetoresistivity which in PtTe2 at a temperature T = 1.3 K leads to an increase in the resistivity up to (5 x 10(4))% under a...
Show moreWe present a detailed quantum oscillatory study on the Dirac typeII semimetallic candidates PdTe2 and PtTe2 via the temperature and the angular dependence of the de Haasvan Alphen and Shubnikovde Haas effects. In highquality single crystals of both compounds, i.e., displaying carrier mobilities between 10(3) and 10(4) cm(2)/Vs, we observed a large nonsaturating magnetoresistivity which in PtTe2 at a temperature T = 1.3 K leads to an increase in the resistivity up to (5 x 10(4))% under a magnetic field mu H0 = 62 T. These high mobilities correlate with their light effective masses in the range of 0.04 to 1 bare electron mass according to our measurements. For PdTe2 the experimentally determined Fermi surface crosssectional areas show excellent agreement with those resulting from band structure calculations. Surprisingly, this is not the case for PtTe2, whose agreement between calculations and experiments is relatively poor even when electronic correlations are included in the calculations. Therefore, our study provides strong support for the existence of a Dirac typeII node in PdTe2 and probably also for PtTe2. Band structure calculations indicate that the topologically nontrivial bands of PtTe2 do not cross the Fermi level epsilon(F). In contrast, for PdTe2 the Dirac typeII cone does intersect Bp, although our calculations also indicate that the associated cyclotron orbit on the Fermi surface is located in a distinct k(z) plane with respect to that of the Dirac typeII node. Therefore, it should yield a trivial Berry phase.
Show less  Date Issued
 20180629
 Identifier
 FSU_libsubv1_wos_000436907600002, 10.1103/PhysRevB.97.235154
 Format
 Citation
 Title
 Determination Of The Effective Kinematic Viscosity For The Decay Of Quasiclassical Turbulence In Superfluid He4.
 Creator

Gao, J., Guo, W., Vinen, W. F.
 Abstract/Description

The energy dissipation of quasiclassical homogeneous turbulence in superfluid He4 (He II) is controlled by an effective kinematic viscosity nu', which relates the energy decay rate dE / dt to the density of quantized vortex lines L as dE / dt = nu'(kappa L)(2). The precise value of nu' is of fundamental importance in developing our understanding of the dissipation mechanism in He II, and it is also needed in many highReynoldsnumber turbulence experiments and model testing that use He II...
Show moreThe energy dissipation of quasiclassical homogeneous turbulence in superfluid He4 (He II) is controlled by an effective kinematic viscosity nu', which relates the energy decay rate dE / dt to the density of quantized vortex lines L as dE / dt = nu'(kappa L)(2). The precise value of nu' is of fundamental importance in developing our understanding of the dissipation mechanism in He II, and it is also needed in many highReynoldsnumber turbulence experiments and model testing that use He II as the working fluid. However, a reliable determination of nu' requires the measurements of both E(t) and L(t), which was never achieved. Here we discuss our study of the quasiclassical turbulence that emerges in the decay of thermal counterflow in He II above 1 K. We were able to measure E(t) by using a recently developed flowvisualization technique and L(t) via secondsound attenuation. We report the nu' values in a wide temperature range determined from a comparison of the time evolution of E(t) and L(t).
Show less  Date Issued
 20160901
 Identifier
 FSU_libsubv1_wos_000383033500004, 10.1103/PhysRevB.94.094502
 Format
 Citation
 Title
 Dipolaroctupolar Ising Antiferromagnetism In Sm2ti2o7: A Moment Fragmentation Candidate.
 Creator

Mauws, C., Hallas, A. M., Sala, G., Aczel, A. A., Sarte, P. M., Gaudet, J., Ziat, D., Quilliam, J. A., Lussier, J. A., Bieringer, M., Zhou, H. D., Wildes, A., Stone, I. M. B.,...
Show moreMauws, C., Hallas, A. M., Sala, G., Aczel, A. A., Sarte, P. M., Gaudet, J., Ziat, D., Quilliam, J. A., Lussier, J. A., Bieringer, M., Zhou, H. D., Wildes, A., Stone, I. M. B., Abernathy, D., Luke, G. M., Gaulin, B. D., Wiebe, C. R.
Show less  Abstract/Description

Over the past two decades, the magnetic ground states of all rareearth titanate pyrochlores have been extensively studied, with the exception of Sm2Ti2O7. This is, in large part, due to the very high absorption cross section of naturally occurring samarium, which renders neutron scattering infeasible. To combat this, we have grown a large, isotopically enriched single crystal of Sm2Ti2O7. Using inelastic neutron scattering, we determine that the crystal field ground state for Sm3+ is a...
Show moreOver the past two decades, the magnetic ground states of all rareearth titanate pyrochlores have been extensively studied, with the exception of Sm2Ti2O7. This is, in large part, due to the very high absorption cross section of naturally occurring samarium, which renders neutron scattering infeasible. To combat this, we have grown a large, isotopically enriched single crystal of Sm2Ti2O7. Using inelastic neutron scattering, we determine that the crystal field ground state for Sm3+ is a dipolaroctupolar doublet with Ising anisotropy. Neutron diffraction experiments reveal that Sm2Ti2O7 orders into the allin, allout magnetic structure with an ordered moment of 0.44(7)mu(B) below TN = 0.35 K, consistent with expectations for antiferromagnetically coupled Ising spins on the pyrochlore lattice. Zerofield muon spin relaxation measurements reveal an absence of spontaneous oscillations and persistent spin fluctuations down to 0.03 K. The combination of the dipolaroctupolar nature of the Sm3+ moment, the allin, allout ordered state, and the lowtemperature persistent spin dynamics make this material an intriguing candidate for moment fragmentation physics.
Show less  Date Issued
 20180905
 Identifier
 FSU_libsubv1_wos_000443672100001, 10.1103/PhysRevB.98.100401
 Format
 Citation
 Title
 Dissipation In Quantum Turbulence In Superfluid He4 Above 1 K.
 Creator

Gao, J., Guo, W., Yui, S., Tsubota, M., Vinen, W. F.
 Abstract/Description

There are two commonly discussed forms of quantum turbulence in superfluid He4 above 1 K: in one there is a random tangle of quantized vortex lines, existing in the presence of a nonturbulent normal fluid; in the second there is a coupled turbulent motion of the two fluids, often exhibiting quasiclassical characteristics on scales larger than the separation between the quantized vortex lines in the superfluid component. The decay of vortex line density, L, in the former case is often...
Show moreThere are two commonly discussed forms of quantum turbulence in superfluid He4 above 1 K: in one there is a random tangle of quantized vortex lines, existing in the presence of a nonturbulent normal fluid; in the second there is a coupled turbulent motion of the two fluids, often exhibiting quasiclassical characteristics on scales larger than the separation between the quantized vortex lines in the superfluid component. The decay of vortex line density, L, in the former case is often described by the equation dL/dt = chi 2 (kappa/2 pi)L2, where kappa is the quantum of circulation and chi(2). is a dimensionless parameter of order unity. The decay of total turbulent energy, E, in the second case is often characterized by an effective kinematic viscosity, v', such that dE/dt = v'kappa L2(2). We present values of chi(2 )derived from numerical simulations and from experiment, which we compare with those derived from a theory developed by Vinen and Niemela. We summarize what is presently known about the values of v' from experiment, and we present a brief introductory discussion of the relationship between chi(2 )and v', leaving a more detailed discussion to a later paper.
Show less  Date Issued
 20180529
 Identifier
 FSU_libsubv1_wos_000433287200005, 10.1103/PhysRevB.97.184518
 Format
 Citation
 Title
 Effective twodimensional thickness for the BerezinskiiKosterlitzThoulesslike transition in a highly underdoped La2xSrxCuO4.
 Creator

Baity, P. G., Shi, Xiaoyan, Shi, Zhenzhong, Benfatto, L., Popovic, Dragana
 Abstract/Description

The nature of the superconducting transition in highly underdoped thick films of La2xSrxCuO4 (x = 0.07 and 0.08) has been investigated using the inplane transport measurements. The contribution of superconducting fluctuations to the conductivity in zero magnetic field, or paraconductivity, was determined from the magnetoresistance measured in fields applied perpendicular to the CuO2 planes. Both the temperature dependence of the paraconductivity above the transition and the nonlinear...
Show moreThe nature of the superconducting transition in highly underdoped thick films of La2xSrxCuO4 (x = 0.07 and 0.08) has been investigated using the inplane transport measurements. The contribution of superconducting fluctuations to the conductivity in zero magnetic field, or paraconductivity, was determined from the magnetoresistance measured in fields applied perpendicular to the CuO2 planes. Both the temperature dependence of the paraconductivity above the transition and the nonlinear currentvoltage (I  V) characteristics measured across it exhibit the main signatures of the BerezinskiiKosterlitzThouless (BKT) transition. The quantitative comparison of the superfluid stiffness, extracted from the I  V data, with the renormalizationgroup results for the BKT theory, reveals a large value of the vortexcore energy. This finding is confirmed by the analysis of the paraconductivity obtained using different methods. The results strongly suggest that the characteristic energy scale controlling the BKT behavior in this layered system corresponds to the superfluid stiffness of a few layers.
Show less  Date Issued
 20160125
 Identifier
 FSU_libsubv1_wos_000369218500009, 10.1103/PhysRevB.93.024519
 Format
 Citation
 Title
 Effects Of Stuffing On The Atomic And Electronic Structure Of The Pyrochlore Yb2ti2o7.
 Creator

Ghosh, Soham S., Manousakis, Efstratios
 Abstract/Description

There are reasons to believe that the ground state of the magnetic rareearth pyrochlore Yb(2)Ti2O(7) is on the boundary between competing ground states. We have carried out ab initio density functional calculations to determine the most stable chemical formula as a function of the oxygen chemical potential and the likely location of the oxygen atoms in the unit cell of the "stuffed" system. We find that it is energetically favorable in the stuffed crystal (with an Yb replacement on a Ti site...
Show moreThere are reasons to believe that the ground state of the magnetic rareearth pyrochlore Yb(2)Ti2O(7) is on the boundary between competing ground states. We have carried out ab initio density functional calculations to determine the most stable chemical formula as a function of the oxygen chemical potential and the likely location of the oxygen atoms in the unit cell of the "stuffed" system. We find that it is energetically favorable in the stuffed crystal (with an Yb replacement on a Ti site) to contain oxygen vacancies which dope the Yb 4f orbitals and qualitatively change the electronic properties of the system. In addition, with the inclusion of the contribution of spinorbit coupling (SOC) on top of the GGA + U approach, we investigated the electronic structure and the magnetic moments of the most stable stuffed system. In our determined stuffed structure the valence bands as compared to those of the pure system are pushed down and a change in hybridization between the O 2p orbitals and the metal ion states is found. Our firstprinciple findings should form a foundation for effective models describing the lowtemperature properties of this material whose true ground state remains controversial.
Show less  Date Issued
 20180611
 Identifier
 FSU_libsubv1_wos_000434762500006, 10.1103/PhysRevB.97.245117
 Format
 Citation
 Title
 Effects Of Uniaxial Pressure On The Quantum Tunneling Of Magnetization In A Highsymmetry Mn12 Singlemolecule Magnet.
 Creator

Atkinson, James H., Fournet, Adeline D., Bhaskaran, Lakshmi, Myasoedov, Yuri, Zeldov, Eli, del Barco, Enrique, Hill, Stephen, Christou, George, Friedman, Jonathan R.
 Abstract/Description

The symmetry of singlemolecule magnets dictates their spin quantum dynamics, influencing how such systems relax via quantum tunneling of magnetization (QTM). By reducing a system's symmetry, through the application of a magnetic field or uniaxial pressure, these dynamics can be modified. We report measurements of the magnetization dynamics of a crystalline sample of the highsymmetry [Mn12O12(O2CMe)(16)(MeOH)(4)] center dot MeOH singlemolecule magnet as a function of uniaxial pressure...
Show moreThe symmetry of singlemolecule magnets dictates their spin quantum dynamics, influencing how such systems relax via quantum tunneling of magnetization (QTM). By reducing a system's symmetry, through the application of a magnetic field or uniaxial pressure, these dynamics can be modified. We report measurements of the magnetization dynamics of a crystalline sample of the highsymmetry [Mn12O12(O2CMe)(16)(MeOH)(4)] center dot MeOH singlemolecule magnet as a function of uniaxial pressure applied either parallel or perpendicular to the sample's "easy" magnetization axis. At temperatures between 1.8 and 3.3 K, magnetic hysteresis loops exhibit the characteristic steplike features that signal the occurrence of QTM. After applying uniaxial pressure to the sample in situ, both the magnitude and field position of the QTM steps changed. The step magnitudes were observed to grow as a function of pressure in both arrangements of pressure, while pressure applied along (perpendicular to) the sample's easy axis caused the resonanttunneling fields to increase (decrease). These observations were compared with simulations in which the system's Hamiltonian parameters were changed. From these comparisons, we determined that parallel pressure induces changes to the secondorder axial anisotropy parameter as well as either the fourthorder axial or fourthorder transverse parameter, or to both. In addition, we find that pressure applied perpendicular to the easy axis induces a rhombic anisotropy E approximate to D/2000 per kbar that can be understood as deriving from a symmetrybreaking distortion of the molecule.
Show less  Date Issued
 20170504
 Identifier
 FSU_libsubv1_wos_000400657600001, 10.1103/PhysRevB.95.184403
 Format
 Citation
 Title
 Electrical Transport Properties Of Singlecrystal Cab6, Srb6, And Bab6.
 Creator

Stankiewicz, Jolanta, Rosa, Priscila F. S., Schlottmann, Pedro, Fisk, Zachary
 Abstract/Description

The electrical resistivity and Hall effect of alkalineearthmetal hexaboride single crystals are measured as a function of temperature, hydrostatic pressure, and magnetic field. The transport properties vary weakly with the external parameters and are modeled in terms of intrinsic variablevalence defects. These defects can stay either in (1) delocalized shallow levels or in (2) localized levels resonant with the conduction band, which can be neutral or negatively charged. Satisfactory...
Show moreThe electrical resistivity and Hall effect of alkalineearthmetal hexaboride single crystals are measured as a function of temperature, hydrostatic pressure, and magnetic field. The transport properties vary weakly with the external parameters and are modeled in terms of intrinsic variablevalence defects. These defects can stay either in (1) delocalized shallow levels or in (2) localized levels resonant with the conduction band, which can be neutral or negatively charged. Satisfactory agreement is obtained for electronic transport properties in a broad temperature and pressure range, although fitting the magnetoresistance is less straightforward and a combination of various mechanisms is needed to explain the field and temperature dependences.
Show less  Date Issued
 20160922
 Identifier
 FSU_libsubv1_wos_000383865700005, 10.1103/PhysRevB.94.125141
 Format
 Citation
 Title
 Electron spin resonance in a twodimensional Fermi liquid with spinorbit coupling.
 Creator

Maiti, Saurabh, Imran, Muhammad, Maslov, Dmitrii L.
 Abstract/Description

Electron spin resonance (ESR) is usually viewed as a singleparticle phenomenon protected from the effect of manybody correlations. We show that this is not the case in a twodimensional Fermi liquid (FL) with spinorbit coupling (SOC). Depending on whether the inplane magnetic field is below or above some critical value, ESR in such a system probes up to three chiralspin collective modes, augmented by the spin mode in the presence of the field, or the SilinLeggett mode. All the modes are...
Show moreElectron spin resonance (ESR) is usually viewed as a singleparticle phenomenon protected from the effect of manybody correlations. We show that this is not the case in a twodimensional Fermi liquid (FL) with spinorbit coupling (SOC). Depending on whether the inplane magnetic field is below or above some critical value, ESR in such a system probes up to three chiralspin collective modes, augmented by the spin mode in the presence of the field, or the SilinLeggett mode. All the modes are affected by both SOC and FL renormalizations. We argue that ESR can be used as a probe not only for SOC but also for manybody physics.
Show less  Date Issued
 20160126
 Identifier
 FSU_libsubv1_wos_000369223400008, 10.1103/PhysRevB.93.045134
 Format
 Citation
 Title
 Electronhole asymmetry, Dirac fermions, and quantum magnetoresistance in BaMnBi2.
 Creator

Li, Lijun, Wang, Kefeng, Graf, D., Wang, Limin, Wang, Aifeng, Petrovic, C.
 Abstract/Description

We report twodimensional quantum transport and Dirac fermions in BaMnBi2 single crystals. BaMnBi2 is a layered bad metal with highly anisotropic conductivity and magnetic order below 290 K. Magnetotransport properties, nonzero Berry phase, small cyclotronmass, and the firstprinciples band structure calculations indicate the presence of Dirac fermions in Bi square nets. Quantum oscillations in the Hall channel suggest the presence of both electron and hole pockets, whereas Dirac and...
Show moreWe report twodimensional quantum transport and Dirac fermions in BaMnBi2 single crystals. BaMnBi2 is a layered bad metal with highly anisotropic conductivity and magnetic order below 290 K. Magnetotransport properties, nonzero Berry phase, small cyclotronmass, and the firstprinciples band structure calculations indicate the presence of Dirac fermions in Bi square nets. Quantum oscillations in the Hall channel suggest the presence of both electron and hole pockets, whereas Dirac and parabolic states coexist at the Fermi level.
Show less  Date Issued
 20160328
 Identifier
 FSU_libsubv1_wos_000372799100001, 10.1103/PhysRevB.93.115141
 Format
 Citation
 Title
 Emergent Quasionedimensionality In A Kagome Magnet: A Simple Route To Complexity.
 Creator

Gong, ShouShu, Zhu, Wei, Yang, Kun, Starykh, Oleg A., Sheng, D. N., Balents, Leon
 Abstract/Description

We study the groundstate phase diagram of the quantum spin1/2 Heisenberg model on the kagome lattice with first(J(1) 0) by means of analytical lowenergy field theory and numerical densitymatrix renormalization group (DMRG) studies. The results offer a consistent picture of the J(d)dominant regime in terms of three sets of spin chains weakly coupled by the ferromagnetic interchain interactions J(1,2). When either J(1) or J(2) is much stronger than the other one, the model is found to...
Show moreWe study the groundstate phase diagram of the quantum spin1/2 Heisenberg model on the kagome lattice with first(J(1) < 0), second(J(2) < 0), and thirdneighbor interactions (J(d) > 0) by means of analytical lowenergy field theory and numerical densitymatrix renormalization group (DMRG) studies. The results offer a consistent picture of the J(d)dominant regime in terms of three sets of spin chains weakly coupled by the ferromagnetic interchain interactions J(1,2). When either J(1) or J(2) is much stronger than the other one, the model is found to support one of two cuboctohedral phases, cuboc1, and cuboc2. These cuboc states host noncoplanar longranged magnetic order and possess finite scalar spin chirality. However, in the compensated regime J(1) similar or equal to J(2), a valence bond crystal phase emerges between the two cuboc phases. We find excellent agreement between an analytical theory based on coupled spin chains and unbiased DMRG calculations, including at a very detailed level of comparison of the structure of the valence bond crystal state. To our knowledge, this is the first such comprehensive understanding of a highly frustrated twodimensional quantum antiferromagnet. We find no evidence of either the onedimensional gapless spin liquid or the chiral spin liquids, which were previously suggested by parton meanfield theories.
Show less  Date Issued
 20160727
 Identifier
 FSU_libsubv1_wos_000381482700001, 10.1103/PhysRevB.94.035154
 Format
 Citation
 Title
 Emergent Spin1 Trimerized Valence Bond Crystal In The Spin1/2 Heisenberg Model On The Star Lattice.
 Creator

Ran, ShiJu, Li, Wei, Gong, ShouShu, Weichselbaum, Andreas, von Delft, Jan, Su, Gang
 Abstract/Description

We explore the frustrated spin1/2 Heisenberg model on the star lattice with antiferromagnetic (AF) couplings inside each triangle and ferromagnetic (FM) intertriangle couplings (J(e)
Show moreWe explore the frustrated spin1/2 Heisenberg model on the star lattice with antiferromagnetic (AF) couplings inside each triangle and ferromagnetic (FM) intertriangle couplings (J(e) < 0), and calculate its magnetic and thermodynamic properties. We show that the FM couplings do not sabotage the magnetic disordering of the ground state due to the frustration from the AF interactions inside each triangle, but trigger a fully gapped inversionsymmetrybreaking trimerized valence bond crystal (TVBC) with emergent spin1 degrees of freedom. We discover that with strengthening J(e), the system exhibits a universal scaling behavior either with or without a magnetic field h: the order parameter, the five critical fields that separate the J(e)h groundstate phase diagram into six phases, and the excitation gap obtained by lowtemperature specific heat, all depend exponentially on J(e). Our work implies that the spin1 VBCs can be stabilized by introducing small FM couplings in the geometrically frustrated spin1/2 systems.
Show less  Date Issued
 20180226
 Identifier
 FSU_libsubv1_wos_000426042500002, 10.1103/PhysRevB.97.075146
 Format
 Citation
 Title
 Energylevel Statistics In Strongly Disordered Systems With Powerlaw Hopping.
 Creator

Titum, Paraj, Quito, Victor L., Syzranov, Sergey
 Abstract/Description

Motivated by neutral excitations in disordered electronic materials and systems of trapped ultracold particles with longrange interactions, we study energylevel statistics of quasiparticles with the powerlaw hopping Hamiltonian proportional to 1/r(alpha) in a strong random potential. In solidstate systems such quasiparticles, which are exemplified by neutral dipolar excitations, lead to longrange correlations of local observables and may dominate energy transport. Focusing on the...
Show moreMotivated by neutral excitations in disordered electronic materials and systems of trapped ultracold particles with longrange interactions, we study energylevel statistics of quasiparticles with the powerlaw hopping Hamiltonian proportional to 1/r(alpha) in a strong random potential. In solidstate systems such quasiparticles, which are exemplified by neutral dipolar excitations, lead to longrange correlations of local observables and may dominate energy transport. Focusing on the excitations in disordered electronic systems, we compute the energylevel correlation function R2(omega) in a finite system in the limit of sufficiently strong disorder. At small energy differences, the correlations exhibit WignerDyson statistics. In particular, in the limit of very strong disorder the energylevel correlation function is given by R2(omega, V) = A(3) omega/omega(V) for small frequencies omega << omega(V) and R2(omega, V) = 1  (alpha  d)A(1) (omega(V)/omega)(d/alpha)  A(2) (omega(V)/omega)(2) for large frequencies omega << omega(V), where omega(V) proportional to Valpha/d is the characteristic matrix element of excitation hopping in a system of volume V, and A(1), A(2), and A(3) are coefficients of order unity which depend on the shape of the system. The energylevel correlation function, which we study, allows for a direct experimental observation, for example, by measuring the correlations of the ac conductance of the system at different frequencies.
Show less  Date Issued
 20180716
 Identifier
 FSU_libsubv1_wos_000438672400001, 10.1103/PhysRevB.98.014201
 Format
 Citation
 Title
 Entanglement Entropy And Topological Order In Resonating Valencebond Quantum Spin Liquids.
 Creator

Wildeboer, Julia, Seidel, Alexander, Melko, Roger G.
 Abstract/Description

On the triangular and kagome lattices, shortranged resonating valencebond wave functions can be sampled without the sign problem using a recently developed Pfaffian Monte Carlo scheme. In this Rapid Communication, we study the Renyi entanglement entropy in these wave functions using a replicatrick method. Using various spatial bipartitions, including the LevinWen construction, our finitesize scaled Renyi entropy gives a topological contribution consistent with. gamma = ln( 2), as...
Show moreOn the triangular and kagome lattices, shortranged resonating valencebond wave functions can be sampled without the sign problem using a recently developed Pfaffian Monte Carlo scheme. In this Rapid Communication, we study the Renyi entanglement entropy in these wave functions using a replicatrick method. Using various spatial bipartitions, including the LevinWen construction, our finitesize scaled Renyi entropy gives a topological contribution consistent with. gamma = ln( 2), as expected for a gapped Z(2) quantum spin liquid. We prove that the mutual statistics is consistent with the toric code anyon model and rule out any other quasiparticle statistics such as the double semion model.
Show less  Date Issued
 20170306
 Identifier
 FSU_libsubv1_wos_000396000700001, 10.1103/PhysRevB.95.100402
 Format
 Citation
 Title
 Equilibrium, metastability, and hysteresis in a model spincrossover material with nearestneighbor antiferromagneticlike and longrange ferromagneticlike interactions.
 Creator

Rikvold, Per Arne, Brown, Gregory, Miyashita, Seiji, Omand, Conor, Nishino, Masamichi
 Abstract/Description

Phase diagrams and hysteresis loops were obtained by Monte Carlo simulations and a mean field method for a simplified model of a spincrossovermaterialwith a twostep transition between the highspin and lowspin states. This model is a mapping onto a squarelattice S = 1/2 Ising model with antiferromagnetic nearestneighbor and ferromagnetic HusimiTemperley ( equivalentneighbor) longrange interactions. Phase diagrams obtained by the two methods for weak and strong longrange interactions...
Show morePhase diagrams and hysteresis loops were obtained by Monte Carlo simulations and a mean field method for a simplified model of a spincrossovermaterialwith a twostep transition between the highspin and lowspin states. This model is a mapping onto a squarelattice S = 1/2 Ising model with antiferromagnetic nearestneighbor and ferromagnetic HusimiTemperley ( equivalentneighbor) longrange interactions. Phase diagrams obtained by the two methods for weak and strong longrange interactions are found to be similar. However, for intermediatestrength longrange interactions, the Monte Carlo simulations show that tricritical points decompose into pairs of critical end points and meanfield critical points surrounded by hornshaped regions of metastability. Hysteresis loops along paths traversing the horn regions are strongly reminiscent of thermal twostep transition loops with hysteresis, recently observed experimentally in several spincrossover materials. We believe analogous phenomena should be observable in experiments and simulations for many systems that exhibit competition between local antiferromagneticlike interactions and longrange ferromagneticlike interactions caused by elastic distortions.
Show less  Date Issued
 20160216
 Identifier
 FSU_libsubv1_wos_000370244600002, 10.1103/PhysRevB.93.064109
 Format
 Citation
 Title
 Evidence For Correlated Dynamics Near The Berezinskiikosterlitzthoulesslike Transition In Highly Underdoped La2xsrxcuo4.
 Creator

Shi, Zhenzhong, Shi, Xiaoyan, Popovic, Dragana
 Abstract/Description

A lowfrequency resistance noise study in highly underdoped thick films of La2xSrxCuO4 (x = 0.07 and 0.08) reveals slow, correlated dynamics and breaking of ergodicity near the superconducting transition of the BerezinskiiKosterlitzThouless type. The observed correlated behavior is strongly suppressed by disorder.
 Date Issued
 20161005
 Identifier
 FSU_libsubv1_wos_000385239900002, 10.1103/PhysRevB.94.134503
 Format
 Citation
 Title
 Evidence For Impact Ionization In Vanadium Dioxide.
 Creator

Holleman, Joshua, Bishop, Michael M., Garcia, Carlos, Winfred, J. S. R. Vellore, Lee, Shinbuhm, Lee, Ho Nyung, Beekman, Christianne, Manousakis, Efstratios, McGill, Stephen A.
 Abstract/Description

Pumpprobe optical spectroscopy was used to investigate proposed chargecarrier multiplication via impact ionization in the M1 insulating phase of VO2. By comparing the transient reflectivities of the film when pumped at less than and then more than twice the bandgap energy, we observed a larger ultrafast response with the higher energy pump color while the film was still transiently in the insulating phase. We additionally identified multiple time scales within the charge dynamics and...
Show morePumpprobe optical spectroscopy was used to investigate proposed chargecarrier multiplication via impact ionization in the M1 insulating phase of VO2. By comparing the transient reflectivities of the film when pumped at less than and then more than twice the bandgap energy, we observed a larger ultrafast response with the higher energy pump color while the film was still transiently in the insulating phase. We additionally identified multiple time scales within the charge dynamics and analyzed how these changed when the pump and probe wavelengths were varied. This experiment provided evidence that a fast carrier multiplication process, i.e., impact ionization, acts efficiently in this prototypical strongly correlated insulator, as was recently predicted by theoretical calculations.
Show less  Date Issued
 20161017
 Identifier
 FSU_libsubv1_wos_000386097100004, 10.1103/PhysRevB.94.155129
 Format
 Citation
 Title
 Extremely Large Nonsaturating Magnetoresistance And Ultrahigh Mobility Due To Topological Surface States In The Metallic Bi2te3 Topological Insulator.
 Creator

Shrestha, K., Chou, M., Graf, D., Yang, H. D., Lorenz, B., Chu, C. W.
 Abstract/Description

Weak antilocalization (WAL) effects in Bi2Te3 single crystals have been investigated at high and low bulk chargecarrier concentrations. At low chargecarrier density the WAL curves scale with the normal component of the magnetic field, demonstrating the dominance of topological surface states in magnetoconductivity. At high chargecarrier density the WAL curves scale with neither the applied field nor its normal component, implying a mixture of bulk and surface conduction. WAL due to...
Show moreWeak antilocalization (WAL) effects in Bi2Te3 single crystals have been investigated at high and low bulk chargecarrier concentrations. At low chargecarrier density the WAL curves scale with the normal component of the magnetic field, demonstrating the dominance of topological surface states in magnetoconductivity. At high chargecarrier density the WAL curves scale with neither the applied field nor its normal component, implying a mixture of bulk and surface conduction. WAL due to topological surface states shows no dependence on the nature (electrons or holes) of the bulk charge carriers. The observations of an extremely large nonsaturating magnetoresistance and ultrahigh mobility in the samples with lower carrier density further support the presence of surface states. The physical parameters characterizing the WAL effects are calculated using the HikamiLarkinNagaoka formula. At high chargecarrier concentrations, there is a greater number of conduction channels and a decrease in the phase coherence length compared to low chargecarrier concentrations. The extremely large magnetoresistance and high mobility of topological insulators have great technological value and can be exploited in magnetoelectric sensors and memory devices.
Show less  Date Issued
 20170508
 Identifier
 FSU_libsubv1_wos_000401229000004, 10.1103/PhysRevB.95.195113
 Format
 Citation
 Title
 Fermi Surface Reconstruction And Dimensional Topology Change In Nddoped Cecoin5.
 Creator

Klotz, J., Goetze, K., Sheikin, I., Foerster, T., Graf, D., Park, J.H., Choi, E. S., Hu, R., Petrovic, C., Wosnitza, J., Green, E. L.
 Abstract/Description

We performed lowtemperature de Haasvan Alphen effect measurements on a Ce1xNdxCoIn5 series, for x = 0.02, 0.05, 0.1, and 1, down to T = 40 mK using torque magnetometry in magnetic fields up to 35 T. Our results indicate that a Fermi surface (FS) reconstruction occurs from a quasitwodimensional topology for Nd2% to a rather threedimensional one for Nd5%, thus reducing the possibility of perfect FS nesting. The FS evolves further with increasing Nd content with no observed divergence of...
Show moreWe performed lowtemperature de Haasvan Alphen effect measurements on a Ce1xNdxCoIn5 series, for x = 0.02, 0.05, 0.1, and 1, down to T = 40 mK using torque magnetometry in magnetic fields up to 35 T. Our results indicate that a Fermi surface (FS) reconstruction occurs from a quasitwodimensional topology for Nd2% to a rather threedimensional one for Nd5%, thus reducing the possibility of perfect FS nesting. The FS evolves further with increasing Nd content with no observed divergence of the effective mass between Nd2% and 10%, consistent with the crossing of a spin density wave type of quantum critical point. Our results elucidate the origin of the Q phase observed at the 5% Nddoping level [Raymond et al., T. Phys. Soc. Jpn. 83, 013707 (2014)].
Show less  Date Issued
 20180809
 Identifier
 FSU_libsubv1_wos_000441234900001, 10.1103/PhysRevB.98.081105
 Format
 Citation
 Title
 Fermi surface reconstruction in FeSe under high pressure.
 Creator

Terashima, Taichi, Kikugawa, Naoki, Kiswandhi, Andhika, Graf, David, Choi, EunSang, Brooks, James S., Kasahara, Shigeru, Watashige, Tatsuya, Matsuda, Yuji, Shibauchi, Takasada,...
Show moreTerashima, Taichi, Kikugawa, Naoki, Kiswandhi, Andhika, Graf, David, Choi, EunSang, Brooks, James S., Kasahara, Shigeru, Watashige, Tatsuya, Matsuda, Yuji, Shibauchi, Takasada, Wolf, Thomas, Boehmer, Anna E., Hardy, Frederic, Meingast, Christoph, Loehneysen, Hilbert V., Uji, Shinya
Show less  Abstract/Description

We report Shubnikovde Haas (SdH) oscillation measurements on FeSe under high pressure up to P = 16.1 kbar. We find a sudden change in SdH oscillations at the onset of the pressureinduced antiferromagnetism at P similar to 8 kbar. We argue that this change can be attributed to a reconstruction of the Fermi surface by the antiferromagnetic order. The negative dT(c)/dP observed in a range between P similar to 8 and 12 kbar may be explained by the reduction in the density of states due to the...
Show moreWe report Shubnikovde Haas (SdH) oscillation measurements on FeSe under high pressure up to P = 16.1 kbar. We find a sudden change in SdH oscillations at the onset of the pressureinduced antiferromagnetism at P similar to 8 kbar. We argue that this change can be attributed to a reconstruction of the Fermi surface by the antiferromagnetic order. The negative dT(c)/dP observed in a range between P similar to 8 and 12 kbar may be explained by the reduction in the density of states due to the reconstruction. The ratio of the transition temperature to the effective Fermi energy remains high under high pressure: k(B)T(c)/EF similar to 0.1 even at P = 16.1 kbar.
Show less  Date Issued
 20160303
 Identifier
 FSU_libsubv1_wos_000371401700003, 10.1103/PhysRevB.93.094505
 Format
 Citation
 Title
 Ferromagnetic Quantum Critical Point In Cepd2p2 With Pd > Ni Substitution.
 Creator

Lai, Y., Bone, S. E., Minasian, S., Ferrier, M. G., LezamaPacheco, J., Mocko, V., Ditter, A. S., Kozimor, S. A., Seidler, G. T., Nelson, W. L., Chiu, Y.C., Huang, K., Potter,...
Show moreLai, Y., Bone, S. E., Minasian, S., Ferrier, M. G., LezamaPacheco, J., Mocko, V., Ditter, A. S., Kozimor, S. A., Seidler, G. T., Nelson, W. L., Chiu, Y.C., Huang, K., Potter, W., Graf, D., AlbrechtSchmitt, T. E., Baumbach, R. E.
Show less  Abstract/Description

An investigation of the structural, thermodynamic, and electronic transport properties of the isoelectronic chemical substitution series Ce(Pd1x Nix)(2)P2 is reported, where a possible ferromagnetic quantum critical point is uncovered in the temperatureconcentration (Tx) phase diagram. This behavior results from the simultaneous contraction of the unit cell volume, which tunes the relative strengths of the Kondo and RudermanKittelKasuya Yosida (RKKY) interactions, and the introduction...
Show moreAn investigation of the structural, thermodynamic, and electronic transport properties of the isoelectronic chemical substitution series Ce(Pd1x Nix)(2)P2 is reported, where a possible ferromagnetic quantum critical point is uncovered in the temperatureconcentration (Tx) phase diagram. This behavior results from the simultaneous contraction of the unit cell volume, which tunes the relative strengths of the Kondo and RudermanKittelKasuya Yosida (RKKY) interactions, and the introduction of disorder through alloying. Near the critical region at x(cr) approximate to 0.7, the rate of contraction of the unit cell volume strengthens, indicating that the cerium f valence crosses over from trivalent to a noninteger value. Consistent with this picture, xray absorption spectroscopy measurements reveal that while CePd2P2 has a purely trivalent cerium f state, CeNi2P2 has a small (<10 %) tetravalent contribution. In a broad region around xcr, there is a breakdown of Fermiliquid temperature dependences, signaling the influence of quantum critical fluctuations and disorder effects. Measurements of clean CePd2P2 furthermore showthat applied pressure has an initial effect similar to alloying on the ferromagnetic order. From these results, CePd2P2 emerges as a keystone system to test theories such as the BelitzKirkpatrickVojta model for ferromagnetic quantum criticality, where distinct behaviors are expected in the dirty and clean limits.
Show less  Date Issued
 20180606
 Identifier
 FSU_libsubv1_wos_000434256700002, 10.1103/PhysRevB.97.224406
 Format
 Citation
 Title
 Fieldinduced Magnetic Phase Transitions And Metastable States In Tb3ni.
 Creator

Gubkin, A. F., Wu, L. S., Nikitin, S. E., Suslov, A. V., Podlesnyak, A., Prokhnenko, O., Prokes, K., Yokaichiya, F., Keller, L., Baranov, N. V.
 Abstract/Description

In this paper we report the detailed study of magnetic phase diagrams, lowtemperature magnetic structures, and the magnetic field effect on the electrical resistivity of the binary intermetallic compound Tb3Ni. The incommensurate magnetic structure of the spindensitywave type described with magnetic superspace group P112(1)/a1'(ab0)0ss and propagation vector k(IC) = [0.506, 0.299,0] was found to emerge just below Neel temperature TN = 61 K. Further cooling below 58 K results in the...
Show moreIn this paper we report the detailed study of magnetic phase diagrams, lowtemperature magnetic structures, and the magnetic field effect on the electrical resistivity of the binary intermetallic compound Tb3Ni. The incommensurate magnetic structure of the spindensitywave type described with magnetic superspace group P112(1)/a1'(ab0)0ss and propagation vector k(IC) = [0.506, 0.299,0] was found to emerge just below Neel temperature TN = 61 K. Further cooling below 58 K results in the appearance of multicomponent magnetic states: (i) a combination of k(1) = [1/2, 1/2, 0] and k(IC) in the temperature range 51 < T < 58 K; (ii) a mixed magnetic state of k(IC), k(1), and k(2) = [1/2, 1/4, 0] with the partially lockedin incommensurate component in the temperature range 48 < T < 51 K; and (iii) a lowtemperature magnetic structure that is described by the intersection of two isotropy subgroups associated with the irreducible representations of two coupled primary order parameters (OPs) k(2) = [1/2, 1/4, 0] and k(3) = [1/2, 1/3, 0] and involves irreducible representations of the secondary OPs k(1) = [1/2, 1/2, 0] and k(4) = [1/2, 0, 0] below 48 K. An external magnetic field suppresses the complex lowtemperature antiferromagnetic states and induces metamagnetic transitions towards a forced ferromagnetic state that are accompanied by a substantial magnetoresistance effect due to the magnetic superzone effect. The forced ferromagnetic state induced after application of an external magnetic field along the b and c crystallographic axes was found to be irreversible below 3 and 8 K, respectively.
Show less  Date Issued
 20180426
 Identifier
 FSU_libsubv1_wos_000430908700001, 10.1103/PhysRevB.97.134425
 Format
 Citation
 Title
 Fieldinduced Spin Splitting And Anomalous Photoluminescence Circular Polarization In Ch3nh3pbi3 Films At High Magnetic Field.
 Creator

Zhang, Chuang, Sun, Dali, Yu, ZhiGang, Sheng, ChuanXiang, McGill, Stephen, Semenov, Dmitry, Vardeny, Zeev Valy
 Abstract/Description

The organicinorganic hybrid perovskites show excellent optical and electrical properties for photovoltaic and a myriad of other optoelectronics applications. Using highfield magnetooptical measurements up to 17.5 T at cryogenic temperatures, we have studied the spindependent optical transitions in the prototype CH3NH3PbI3, which are manifested in the fieldinduced circularly polarized photoluminescence emission. The energy splitting between left and right circularly polarized emission...
Show moreThe organicinorganic hybrid perovskites show excellent optical and electrical properties for photovoltaic and a myriad of other optoelectronics applications. Using highfield magnetooptical measurements up to 17.5 T at cryogenic temperatures, we have studied the spindependent optical transitions in the prototype CH3NH3PbI3, which are manifested in the fieldinduced circularly polarized photoluminescence emission. The energy splitting between left and right circularly polarized emission bands is measured to be similar to 1.5 meV at 17.5 T, from which we obtained an exciton effective g factor of similar to 1.32. Also from the photoluminescence diamagnetic shift we estimate the exciton binding energy to be similar to 17 meV at low temperature. Surprisingly, the corresponding fieldinduced circular polarization is "anomalous" in that the photoluminescence emission of the higher split energy band is stronger than that of the lower split band. This "reversed" intensity ratio originates from the combination of long electron spin relaxation time and hole negative g factor in CH3NH3PbI3, which are in agreement with a model based on the k.p effectivemass approximation.
Show less  Date Issued
 20180416
 Identifier
 FSU_libsubv1_wos_000430055800003, 10.1103/PhysRevB.97.134412
 Format
 Citation
 Title
 Forbidden Coherent Transfer Observed Between Two Realizations Of Quasiharmonic Spin Systems.
 Creator

Bertaina, S., Yue, G., Dutoit, C.E., Chiorescu, I.
 Abstract/Description

The multilevel system Mn55(2 vertical bar) is used to generate two pseudoharmonic level systems, as representations of the same electronic sextuplet at different nuclear spin projections. The systems are coupled using a forbidden nuclear transition induced by the crystalline anisotropy. We demonstrate Rabi oscillations between the two representations in conditions similar to two coupled pseudoharmonic quantum oscillators. Rabi oscillations are performed at a detuned pumping frequency which...
Show moreThe multilevel system Mn55(2 vertical bar) is used to generate two pseudoharmonic level systems, as representations of the same electronic sextuplet at different nuclear spin projections. The systems are coupled using a forbidden nuclear transition induced by the crystalline anisotropy. We demonstrate Rabi oscillations between the two representations in conditions similar to two coupled pseudoharmonic quantum oscillators. Rabi oscillations are performed at a detuned pumping frequency which matches the energy difference between electronuclear states of different oscillators. We measure a coupling stronger than the decoherence rate to indicate the possibility of fast information exchange between the systems.
Show less  Date Issued
 20170720
 Identifier
 FSU_libsubv1_wos_000405913900004, 10.1103/PhysRevB.96.024428
 Format
 Citation
 Title
 Frustrated Magnetism In The Tetragonal Cose Analog Of Superconducting Fese.
 Creator

Wilfong, Brandon, Zhou, Xiuquan, Vivanco, Hector, Campbell, Daniel J., Wang, Kefeng, Graf, Dave, Paglione, Johnpierre, Rodriguez, Efrain
 Abstract/Description

Recently synthesized metastable tetragonal CoSe, isostructural to the FeSe superconductor, offers a new avenue for investigating systems in close proximity to the ironbased superconductors. We present magnetic and transport property measurements on powders and single crystals of CoSe. High field magnetic susceptibility measurements indicate a suppression of the previously reported 10 K ferromagnetic transition with the magnetic susceptibility, exhibiting time dependence below the proposed...
Show moreRecently synthesized metastable tetragonal CoSe, isostructural to the FeSe superconductor, offers a new avenue for investigating systems in close proximity to the ironbased superconductors. We present magnetic and transport property measurements on powders and single crystals of CoSe. High field magnetic susceptibility measurements indicate a suppression of the previously reported 10 K ferromagnetic transition with the magnetic susceptibility, exhibiting time dependence below the proposed transition. Dynamic scaling analysis of the time dependence yields a critical relaxation time of tau* = 0.064 +/ 0.008 s which in turn yields activation energy Ea(*) = 14.84 +/ 0.59 K and an ideal glass temperature T0(*) = 8.91 +/ 0.09 K from VogelFulcher analysis. No transition is observed in resistivity and specific heat measurements, but both measurements indicate that CoSe is metallic. These results are interpreted on the basis of CoSe exhibiting frustrated magnetic ordering arising from competing magnetic interactions. Arrott analysis of single crystal magnetic susceptibility has indicated the transition temperature occurs in close proximity to previous reports and that the magnetic moment lies solely in the ab plane. The results have implications for understanding the relationship between magnetism and transport properties in the iron chalcogenide superconductors.
Show less  Date Issued
 20180308
 Identifier
 FSU_libsubv1_wos_000426901700002, 10.1103/PhysRevB.97.104408
 Format
 Citation
 Title
 Groundstate tuning of metalinsulator transition by compositional variations in BaIr1xRuxO3 (0 <= x <= 1).
 Creator

Yuan, S. J., Butrouna, K., Terzic, J., Zheng, H., Aswartham, S., DeLong, L. E., Ye, Feng, Schlottmann, P., Cao, G.
 Abstract/Description

Hexagonal BaIrO3 is a magnetic insulator driven by the spinorbit interaction (SOI), whereas BaRuO3 is an enhanced paramagnetic metal. Our investigation of structural, magnetic, transport, and thermal properties reveals that substitution of Ru4+ (4d(4)) ions for Ir4+ (5d(5)) ions in BaIrO3 reduces the magnitudes of the SOI and a monoclinic structural distortion and rebalances the competition between the SOI and the lattice degrees of freedom to render an evolution from a magnetic insulting...
Show moreHexagonal BaIrO3 is a magnetic insulator driven by the spinorbit interaction (SOI), whereas BaRuO3 is an enhanced paramagnetic metal. Our investigation of structural, magnetic, transport, and thermal properties reveals that substitution of Ru4+ (4d(4)) ions for Ir4+ (5d(5)) ions in BaIrO3 reduces the magnitudes of the SOI and a monoclinic structural distortion and rebalances the competition between the SOI and the lattice degrees of freedom to render an evolution from a magnetic insulting state to a robust metallic state. The central findings of this paper are as follows: (1) light Ru doping (0 < x <= 0.15) prompts simultaneous, precipitous drops in both the magnetic ordering temperature TN and the electrical resistivity, and (2) heavier Ru doping (0.41 <= x <= 0.9) induces a robust metallic state without any longrange magnetic order. All results suggest a critical role of the lattice degrees of freedom in determining the ground state in the heavy transitionmetal oxides.
Show less  Date Issued
 20160425
 Identifier
 FSU_libsubv1_wos_000374950300008, 10.1103/PhysRevB.93.165136
 Format
 Citation
 Title
 Gutzwiller renormalization group.
 Creator

Lanata, Nicola, Yao, YongXin, Deng, Xiaoyu, Wang, CaiZhuang, Ho, KaiMing, Kotliar, Gabriel
 Abstract/Description

We develop a variational scheme called the "Gutzwiller renormalization group" (GRG), which enables us to calculate the ground state of Anderson impurity models (AIM) with arbitrary numerical precision. Our method exploits the lowentanglement property of the ground state of local Hamiltonians in combination with the framework of the Gutzwiller wave function and indicates that the ground state of the AIM has a very simple structure, which can be represented very accurately in terms of a...
Show moreWe develop a variational scheme called the "Gutzwiller renormalization group" (GRG), which enables us to calculate the ground state of Anderson impurity models (AIM) with arbitrary numerical precision. Our method exploits the lowentanglement property of the ground state of local Hamiltonians in combination with the framework of the Gutzwiller wave function and indicates that the ground state of the AIM has a very simple structure, which can be represented very accurately in terms of a surprisingly small number of variational parameters. We perform benchmark calculations of the singleband AIM that validate our theory and suggest that the GRG might enable us to study complex systems beyond the reach of the other methods presently available and pave the way to interesting generalizations, e.g., to nonequilibrium transport in nanostructures.
Show less  Date Issued
 20160106
 Identifier
 FSU_libsubv1_wos_000367665400002, 10.1103/PhysRevB.93.045103
 Format
 Citation
 Title
 Hall Effect Within The Colossal Magnetoresistive Semimetallic State Of Mote2.
 Creator

Zhou, Qiong, Rhodes, D., Zhang, Q. R., Tang, S., Schoenemann, R., Balicas, L.
 Abstract/Description

Here, we report a systematic study on the Hall effect of the semimetallic state of bulk MoTe2, which was recently claimed to be a candidate for a novel type of Weyl semimetallic state. The temperature (T) dependence of the carrier densities and of their mobilities, as estimated from a numerical analysis based on the isotropic twocarrier model, indicates that its exceedingly large and nonsaturating magnetoresistance may be attributed to a near perfect compensation between the densities of...
Show moreHere, we report a systematic study on the Hall effect of the semimetallic state of bulk MoTe2, which was recently claimed to be a candidate for a novel type of Weyl semimetallic state. The temperature (T) dependence of the carrier densities and of their mobilities, as estimated from a numerical analysis based on the isotropic twocarrier model, indicates that its exceedingly large and nonsaturating magnetoresistance may be attributed to a near perfect compensation between the densities of electrons and holes at low temperatures. A sudden increase in hole density, with a concomitant rapid increase in the electron mobility below T similar to 40 K, leads to comparable densities of electrons and holes at low temperatures suggesting a possible electronic phase transition around this temperature.
Show less  Date Issued
 20160901
 Identifier
 FSU_libsubv1_wos_000383035100001, 10.1103/PhysRevB.94.121101
 Format
 Citation
 Title
 Hybridization Gap In The Heavyfermion Compound Upd2al3 Via Quasiparticle Scattering Spectroscopy.
 Creator

Jaggi, N. K., Mehio, O., Dwyer, M., Greene, L. H., Baumbach, R. E., Tobash, P. H., Bauer, E. D., Thompson, J. D., Park, W. K.
 Abstract/Description

We present results from pointcontact spectroscopy of the antiferromagnetic heavyfermion superconductor UPd2Al3: Conductance spectra are taken from single crystals with two major surface orientations as a function of temperature andmagnetic field and analyzed using a theory of cotunneling into anAnderson lattice. Spectroscopic signatures are clearly identified, including the distinct asymmetric doublepeak structure arising from the opening of a hybridization gap when a coherent heavyFermi...
Show moreWe present results from pointcontact spectroscopy of the antiferromagnetic heavyfermion superconductor UPd2Al3: Conductance spectra are taken from single crystals with two major surface orientations as a function of temperature andmagnetic field and analyzed using a theory of cotunneling into anAnderson lattice. Spectroscopic signatures are clearly identified, including the distinct asymmetric doublepeak structure arising from the opening of a hybridization gap when a coherent heavyFermi liquid is formed. Both the hybridization gap, found to be 7.2 +/ 0.3meV at 4 K, and the conductance enhancement above a flat background decrease upon increasing temperature. While the hybridization gap is extrapolated to remain finite up to similar to 28 K, close to the temperature around which the magnetic susceptibility displays a broad peak, the conductance enhancement vanishes at similar to 18 K, slightly above the antiferromagnetic transition temperature (TN approximate to 14 K). This rapid decrease of the conductance enhancement is understood as a consequence of the junction drifting away from the ballistic regime due to increased scattering off magnons associated with the localized U 5f electrons. This shows that while the hybridization gap opening is not directly associated with the antiferromagnetic ordering, its visibility in the conductance is greatly affected by the temperaturedependent magnetic excitations. Our findings are not only consistent with the 5f dualnature picture in the literature but also shed new light on the interplay between the itinerant and localized electrons in UPd2Al3.
Show less  Date Issued
 20170417
 Identifier
 FSU_libsubv1_wos_000399799500004, 10.1103/PhysRevB.95.165123
 Format
 Citation
 Title
 Incommensurate crystal supercell and polarization flop observed in the magnetoelectric ilmenite MnTiO3.
 Creator

Silverstein, Harlyn J., Skoropata, Elizabeth, Sarte, Paul M., Mauws, Cole, Aczel, Adam A., Choi, Eun Sang, van Lierop, Johan, Wiebe, Christopher R., Zhou, Haidong
 Abstract/Description

MnTiO3 has been studied for many decades, but it was only in the last few years that its magnetoelectric behavior had been observed. Here, we use neutron scattering on two separately grown single crystals and two powder samples to show the presence of a supercell that breaks R (3) over bar symmetry. We also present the temperature and field dependence of the dielectric constant and pyroelectric current and show evidence of nonzero offdiagonal magnetoelectric tensor elements (forbidden by R ...
Show moreMnTiO3 has been studied for many decades, but it was only in the last few years that its magnetoelectric behavior had been observed. Here, we use neutron scattering on two separately grown single crystals and two powder samples to show the presence of a supercell that breaks R (3) over bar symmetry. We also present the temperature and field dependence of the dielectric constant and pyroelectric current and show evidence of nonzero offdiagonal magnetoelectric tensor elements (forbidden by R (3) over bar symmetry) followed by a polarization flop accompanying the spin flop transition at mu H0(SF) = 6.5T. Mossbauer spectroscopy on MnTiO3 gently doped with Fe57 was used to help shed light on the impact of the supercell on the observed behavior. Although the full supercell structure could not be solved at this time due to a lack of visible reflections, the full scope of the results presented here suggest that the role of local spinlattice coupling in the magnetoelectric properties of MnTiO3 is likely more important than previously thought.
Show less  Date Issued
 20160219
 Identifier
 FSU_libsubv1_wos_000370485900001, 10.1103/PhysRevB.93.054416
 Format
 Citation
 Title
 Interactiondriven Fractional Quantum Hall State Of Hardcore Bosons On Kagome Lattice At Onethird Filling.
 Creator

Zhu, W., Gong, S. S., Sheng, D. N.
 Abstract/Description

There has been a growing interest in realizing topologically nontrivial states of matter in band insulators, where a quantum Hall effect can appear as an intrinsic property of the band structure. While ongoing progress is under way with a number of directions, the possibility of realizing novel interactiongenerated topological phases, without the requirement of a nontrivial invariant encoded in singleparticle wave function or band structure, can significantly extend the class of topological...
Show moreThere has been a growing interest in realizing topologically nontrivial states of matter in band insulators, where a quantum Hall effect can appear as an intrinsic property of the band structure. While ongoing progress is under way with a number of directions, the possibility of realizing novel interactiongenerated topological phases, without the requirement of a nontrivial invariant encoded in singleparticle wave function or band structure, can significantly extend the class of topological materials and is thus of great importance. Here, we show an interactiondriven topological phase emerging in an extended BoseHubbard model on a kagome lattice, where the noninteracting band structure is topological trivial with zero Berry curvature in the Brillouin zone. By means of an unbiased stateoftheart densitymatrix renormalization group technique, we identify that the ground state in a broad parameter region is equivalent to a bosonic fractional quantum Hall Laughlin state, based on the characterization of universal properties including groundstate degeneracy, edge excitations, and anyonic quasiparticle statistics. Our work paves a way to finding an interactioninduced topological phase at the phase boundary of conventionally ordered solid phases.
Show less  Date Issued
 20160713
 Identifier
 FSU_libsubv1_wos_000379502800001, 10.1103/PhysRevB.94.035129
 Format
 Citation
 Title
 Interlayer Electronic Transport In Camnbi2 Antiferromagnet.
 Creator

Wang, Aifeng, Graf, D., Wu, Lijun, Wang, Kefeng, Bozin, E., Zhu, Yimei, Petrovic, C.
 Abstract/Description

We report interlayer electronic transport in CaMnBi2 single crystals. Quantum oscillations and angular magnetoresistance suggest coherent electronic conduction and valley polarized conduction of Dirac states. The small cyclotron mass, high mobility of carriers, and nontrivial Berry's phase are consistent with the presence of Dirac fermions on the side wall of the warped cylindrical Fermi surface. Similarly to SrMnBi2, which features an anisotropic Dirac cone, our results suggest that magnetic...
Show moreWe report interlayer electronic transport in CaMnBi2 single crystals. Quantum oscillations and angular magnetoresistance suggest coherent electronic conduction and valley polarized conduction of Dirac states. The small cyclotron mass, high mobility of carriers, and nontrivial Berry's phase are consistent with the presence of Dirac fermions on the side wall of the warped cylindrical Fermi surface. Similarly to SrMnBi2, which features an anisotropic Dirac cone, our results suggest that magneticfieldinduced changes in interlayer conduction are also present in layered bismuthbased materials with a zeroenergy line in momentum space created by the staggered alkaline earth atoms.
Show less  Date Issued
 20160912
 Identifier
 FSU_libsubv1_wos_000383145300004, 10.1103/PhysRevB.94.125118
 Format
 Citation
 Title
 Interplay Of Magnetism And Transport In Hobi.
 Creator

Yang, H.Y., Gaudet, J., Aczel, A. A., Graf, D. E., Blaha, P., Gaulin, B. D., Tafti, Fazel
 Abstract/Description

We report the observation of an extreme magnetoresistance (XMR) in HoBi with a large magnetic moment from Ho f electrons. Neutron scattering is used to determine the magnetic wave vectors across several metamagnetic transitions on the phase diagram of HoBi. Unlike other magnetic rareearth monopnictides, the field dependence of resistivity in HoBi is nonmonotonic and reveals clear signatures of every metamagnetic transition in the lowtemperature and lowfield regime, at T 2.3 T after all...
Show moreWe report the observation of an extreme magnetoresistance (XMR) in HoBi with a large magnetic moment from Ho f electrons. Neutron scattering is used to determine the magnetic wave vectors across several metamagnetic transitions on the phase diagram of HoBi. Unlike other magnetic rareearth monopnictides, the field dependence of resistivity in HoBi is nonmonotonic and reveals clear signatures of every metamagnetic transition in the lowtemperature and lowfield regime, at T < 2 K and H < 2.3 T. The XMR appears at H > 2.3 T after all the metamagnetic transitions are complete and the system is spin polarized by the external magnetic field. The existence of an onset field for XMR and the intimate connection between magnetism and transport in HoBi are unprecedented among the magnetic rareearth monopnictides. Therefore, HoBi provides a unique opportunity to understand the electrical transport in magnetic XMR semimetals.
Show less  Date Issued
 20180727
 Identifier
 FSU_libsubv1_wos_000439974200002, 10.1103/PhysRevB.98.045136
 Format
 Citation
 Title
 Intersubband Scattering In Ngaas/algaas Wide Quantum Wells.
 Creator

Drichko, I. L., Smirnov, I. Yu, Nestoklon, M. O., Suslov, A. V., Kamburov, D., Baldwin, K. W., Pfeiffer, L. N., West, K. W., Golub, L. E.
 Abstract/Description

Slow magnetooscilations of the conductivity are observed in a 75nmwide quantum well at heating of the twodimensional electrons by a highintensity surface acoustic wave. These magnetooscillations are caused by intersubband elastic scattering between the symmetric and asymmetric subbands formed due to an electrostatic barrier in the center of the quantum well. The tunneling splitting between these subbands as well as the intersubband scattering rate are determined.
 Date Issued
 20180220
 Identifier
 FSU_libsubv1_wos_000425492500009, 10.1103/PhysRevB.97.075427
 Format
 Citation
 Title
 Jain2/5 Parent Hamiltonian: Structure Of Zero Modes, Dominance Patterns, And Zero Mode Generators.
 Creator

Chen, Li, Bandyopadhyay, Sumanta, Seidel, Alexander
 Abstract/Description

We analyze general zero mode properties of the parent Hamiltonian of the unprojected Jain2/5 state. We characterize the zero mode condition associated to this Hamiltonian via projection onto a fourdimensional twoparticle subspace for given pair angular momentum, for the disk and similarly for the spherical geometry. Earlier numerical claims in the literature about groundstate uniqueness on the sphere are substantiated on analytic grounds, and related results are derived. Preference is...
Show moreWe analyze general zero mode properties of the parent Hamiltonian of the unprojected Jain2/5 state. We characterize the zero mode condition associated to this Hamiltonian via projection onto a fourdimensional twoparticle subspace for given pair angular momentum, for the disk and similarly for the spherical geometry. Earlier numerical claims in the literature about groundstate uniqueness on the sphere are substantiated on analytic grounds, and related results are derived. Preference is given to secondquantized methods, where zero mode properties are derived not from given analytic wave functions, but from a "lattice" Hamiltonian and associated zero mode conditions. This method reveals new insights into the guidingcenter structure of the unprojected Jain2/5 state, in particular, a system of dominance patterns following a "generalized Pauli principle," which establishes a complete onetoone correspondence with the edge mode counting. We also identify onebody operators that function as generators of zero modes.
Show less  Date Issued
 20170531
 Identifier
 FSU_libsubv1_wos_000402463500001, 10.1103/PhysRevB.95.195169
 Format
 Citation
 Title
 Landaulevel Spectroscopy Of Massive Dirac Fermions In Singlecrystalline Zrte5 Thin Flakes.
 Creator

Jiang, Y., Dun, Z. L., Zhou, H. D., Lu, Z., Chen, K.W., Moon, S., Besara, T., Siegrist, T. M., Baumbach, R. E., Smirnov, D., Jiang, Z.
 Abstract/Description

We report infrared magnetospectroscopy studies on thin crystals of an emerging Dirac material ZrTe5 near the intrinsic limit. The observed structure of the Landaulevel transitions and zerofield infrared absorption indicate a twodimensional Diraclike electronic structure, similar to that in graphene but with a small relativistic mass corresponding to a 9.4meV energy gap. Measurements with circularly polarized light reveal a significant electronhole asymmetry, which leads to splitting of...
Show moreWe report infrared magnetospectroscopy studies on thin crystals of an emerging Dirac material ZrTe5 near the intrinsic limit. The observed structure of the Landaulevel transitions and zerofield infrared absorption indicate a twodimensional Diraclike electronic structure, similar to that in graphene but with a small relativistic mass corresponding to a 9.4meV energy gap. Measurements with circularly polarized light reveal a significant electronhole asymmetry, which leads to splitting of the Landaulevel transitions at high magnetic fields. Our model, based on the BernevigHughesZhang effective Hamiltonian, quantitatively explains all observed transitions, determining the values of the Fermi velocity, Dirac mass (or gap), electronhole asymmetry, and electron and hole g factors.
Show less  Date Issued
 20170705
 Identifier
 FSU_libsubv1_wos_000405026300001, 10.1103/PhysRevB.96.041101
 Format
 Citation