Impact of Pressure on Structural, Vibrational, and Electrical Properties of Nodal-Line Semimetal HfGe_0.92Te

Abstract

The layered nodal-line semimetals hold a fascinating prospect of realizing two-dimensional spin−orbit Dirac points with their diverse ranges of Dirac points near the Fermi level, offering exciting avenues for investigating topological properties. We have explored high-pressure resistivity measurements, in situ Raman spectra, synchrotron X-ray diffraction experiments, and density functional theory calculations on HfGe 0.92 Te single crystals. The Lifshitz transition is observed at 5 GPa, while the structure evolution reveals that the pristine tetragonal structure remains robust within this pressure range. We explore these indirect experimental indications of the transition occurring at 5 GPa, considering the potential Lifshitz transition for HfGe 0.92 Te as inferred from our electronic band structure calculations. This work highlights the significant role of pressure in molding the electronic characteristics of HfGe 0.92 Te and stimulates further exploration of unique electronic behaviors within the broader family of WHM materials, which can be harnessed in the development of electronic devices under extreme conditions.