High Pressure and High Magnetic Field Skin Depth Studies of the Heavy Fermion CeIn₃

CeIn3 belongs to a class of strongly correlated f-electron compounds that show a variety of unusual features like heavy fermion, itinerant and localized antiferromagnetism, non-Fermi liquid behavior and unconventional superconductivity. These interesting properties of the f-electrons arise from the competition of the Kondo effect and the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction. The intensity of these competing interactions is related to the strength of the magnetic exchange interaction between the f-electrons and the conduction electrons, which can be modified by the application of hydrostatic pressure, chemical doping, or magnetic field. The exchange coupling increases under hydrostatic pressure, destroying the long-range antiferromagnetic order, and giving way to new and exciting physics. Hydrostatic high pressure measurements of the skin depth of single crystal CeIn3 samples were performed using a self resonant tank circuit based on a tunnel diode oscillator at 400 mK, 1.5 K. and 4.1 K in magnetic fields up to 64 T. The measurements were carried out at NHMFL's Pulsed Magnet Facility at Los Alamos National Laboratory. At ambient pressure, an anomaly in the skin depth at 45 T and the Neel transition from the antiferromagnetic into the paramagnetic state at 61 T have been observed. The field of the anomaly decreases with applied pressure until approximately 1.0 GPa, where it begins to increase before merging with the antiferromagnetic phase boundary. The field location of the anomaly differs little between measurements performed at 400 mK and 1.5 K, although the transition is markedly smeared at the higher temperature and its position is undeterminable at 4.1 K. The origin of this transport anomaly is a reconstruction of the Fermi surface. Possible explanations of this reconstruction are (i) a collapse of a portion of the Fermi surface in a Lifshitz transition and (ii) a low temperature metamagnetic transition. The critical magnetic field at which the Neel ordered phase is suppressed is also mapped as a function of pressure and extrapolates to the previous ambient pressure measurements at high magnetic fields and high pressure measurements at zero magnetic field.