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 Title
 Landau quantization and spinmomentum locking in topological Kondo insulators.
 Creator

Schlottmann, P.
 Abstract/Description

SmB6 has been predicted to be a strong topological Kondo insulator and experimentally it has been confirmed that at low temperatures the electrical conductivity only takes place at the surfaces of the crystal. Quantum oscillations and ARPES measurements revealed several Dirac cones on the (001) and (101) surfaces of the crystal. We considered three types of surface Dirac cones with an additional parabolic dispersion and studied their Landau quantization and the expectation value of the spin...
Show moreSmB6 has been predicted to be a strong topological Kondo insulator and experimentally it has been confirmed that at low temperatures the electrical conductivity only takes place at the surfaces of the crystal. Quantum oscillations and ARPES measurements revealed several Dirac cones on the (001) and (101) surfaces of the crystal. We considered three types of surface Dirac cones with an additional parabolic dispersion and studied their Landau quantization and the expectation value of the spin of the electrons. The Landau quantization is quite similar in all three cases and would give rise to very similar de Haasvan Alphen oscillations. The spinmomentum locking, on the other hand, differs dramatically. Without the additional parabolic dispersion the spins are locked in the plane of the surface. The parabolic dispersion, however, produces a gradual canting of the spins out of the surface plane. (C) 2016 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License.
Show less  Date Issued
 201605
 Identifier
 FSU_libsubv1_wos_000377962500116, 10.1063/1.4942795
 Format
 Citation
 Title
 Anharmonic Rattling Vibrations Effects In The Esr Of Er3+ Doped Smb6 Kondo Insulator.
 Creator

Lesseux, G. G., Rosa, P. F. S., Fisk, Z., Schlottmann, P., Pagliuso, P. G., Urbano, R. R., Rettori, C.
 Abstract/Description

We report Xband Electron Spin Resonance (ESR) experiments on approximate to 0.2% and approximate to 0.7% Er3+ doped SmB6 at low temperature (4 K  40 K). The crystal field ground state of Er3+ in SmB6 is a 8 quartet with a nearby Gamma(6) excited doublet. The angular dependence of the resonances is not consistent with transitions between pure cubic crystal field states. The data were interpreted in terms of a dynamic JahnTeller (JT) effect by a coupling to Gamma(3) vibrational modes, which...
Show moreWe report Xband Electron Spin Resonance (ESR) experiments on approximate to 0.2% and approximate to 0.7% Er3+ doped SmB6 at low temperature (4 K  40 K). The crystal field ground state of Er3+ in SmB6 is a 8 quartet with a nearby Gamma(6) excited doublet. The angular dependence of the resonances is not consistent with transitions between pure cubic crystal field states. The data were interpreted in terms of a dynamic JahnTeller (JT) effect by a coupling to Gamma(3) vibrational modes, which we propose to originate from the rattling of the small Er3+ ions in the large SmB6 cage. Our data show an anisotropic pair of E and E' resonances at g approximate to 4.4 and two nearly isotropic signals at g approximate to 5.8, one intense and narrow (A vibrational mode) and the other broad and faint, which we attribute to Er3+ ions at lattice sites which are strongly affected by strain, defects and/or extrinsic Al impurities that inhibits the JT effects. Our results are in general consistent with those previously reported by Sturm et al. In addition to the angular dependence of the lines, we discuss the intensities, gvalues and the linewidths of the Er3+ transitions as a function of temperature. (C) 2017 Author(s).
Show less  Date Issued
 201705
 Identifier
 FSU_libsubv1_wos_000402797100076, 10.1063/1.4974914
 Format
 Citation
 Title
 Commensurate and incommensurate spindensity waves in heavy electron systems.
 Creator

Schlottmann, P.
 Abstract/Description

The nesting of the Fermi surfaces of an electron and a hole pocket separated by a nesting vector Q and the interaction between electrons gives rise to itinerant antiferromagnetism. The order can gradually be suppressed by mismatching the nesting and a quantum critical point (QCP) is obtained as the Neel temperature tends to zero. The transfer of pairs of electrons between the pockets can lead to a superconducting dome above the QCP (if Q is commensurate with the lattice, i.e. equal to G/2)....
Show moreThe nesting of the Fermi surfaces of an electron and a hole pocket separated by a nesting vector Q and the interaction between electrons gives rise to itinerant antiferromagnetism. The order can gradually be suppressed by mismatching the nesting and a quantum critical point (QCP) is obtained as the Neel temperature tends to zero. The transfer of pairs of electrons between the pockets can lead to a superconducting dome above the QCP (if Q is commensurate with the lattice, i.e. equal to G/2). If the vector Q is not commensurate with the lattice there are eight possible phases: commensurate and incommensurate spin and charge density waves and four superconductivity phases, two of them with modulated order parameter of the FFLO type. The renormalization group equations are studied and numerically integrated. A reentrant SDW phase (either commensurate or incommensurate) is obtained as a function of the mismatch of the Fermi surfaces and the magnitude of vertical bar Q  G/2 vertical bar. (C) 2016 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License.
Show less  Date Issued
 201605
 Identifier
 FSU_libsubv1_wos_000377962500103, 10.1063/1.4942549
 Format
 Citation