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Free keywords:
Ground state, Hafnium compounds, Hydrostatic pressure, Quantum theory, Tellurium compounds, Ambient pressures, Crystalline structure, Electrical transport properties, High magnetic fields, Insulating phase, Lifshitz transition, Low pressures, Lows-temperatures, Semimetallics, Topological phase, Quantum Hall effect
Abstract:
At ambient pressure, HfTe5 is a material at the boundary between a weak and a strong topological phase, which can be tuned by changes in its crystalline structure or by the application of high magnetic fields. It exhibits a Lifshitz transition upon cooling, and three-dimensional (3D) quantum Hall effect (QHE) plateaus can be observed at low temperatures. Here, we have investigated the electrical transport properties of HfTe5 under hydrostatic pressure up to 3 GPa. We find a pressure-induced crossover from a semimetallic phase at low pressures to an insulating phase at about 1.5 GPa. Our data suggest the presence of a pressure-induced Lifshitz transition at low temperatures within the insulating phase around 2 GPa. The quasi-3D QHE is confined to the low-pressure region in the semimetallic phase. This reveals the importance of the semimetallic ground state for the emergence of the QHE in HfTe5 and thus favors a scenario based on a low carrier density metal in the quantum limit for the observed signatures of the quasiquantized 3D QHE. © 2024 authors. Published by the American Physical Society.
