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Special Seminar | X-Ray Science Division

Phase Transitions in Diamond-Anvil-Cell Compressed CePd2P2 and BixTeI

XSD/MM Special Presentation

Abstract: At ambient conditions, the compound CePd2P2 exists in the ThCr2S2 structure and orders ferromagnetically at 29 K. A combination of resistivity, magnetic susceptibility, and x-ray diffraction measurements were performed to examine the temperature-pressure-magnetic field phase diagram in CePd2P2. These results show that the ferromagnetic transition temperature is reduced by sustained mechanical pressure and abruptly drops to 0 K at approximately 12 GPa. We also compare our results to prior work by Lai et al. who studied the effects of chemical pressure produced via Pd-to-Ni substitution, finding that the transition temperature reaches 0 K at a cell volume of approximately 156 Å3 in both cases. 

The topological insulator Bi2TeI and the topological metal Bi3TeI show no signs of phase transitions between 2 and 300 K at ambient pressure. However, application of mechanical pressure through a diamond-anvil cell reveals a number of interesting properties in both compounds. Despite their different crystal structures at ambient pressure, x-ray diffraction reveals that both transition to a disordered bcc structure under sufficient pressure. Furthermore, resistivity and magnetic susceptibility measurements reveal superconductivity emerges at approximately 13 GPa in Bi2TeI and 11.5 GPa in Bi3TeI.