Anomalous Transport Behavior in the Vicinity of a Topological Phase Transition in ZrTe5

Abstract

Understanding the impact of topology on electrical transport properties is currently an area of intense research, motivated by the potential application of engineering materials with physical properties that are protected by the underlying topology. Often, it is difficult to distinguish the root mechanism for measured transport phenomenon. To inspect if topology is responsible for measured phenomena, it is desirable to have a tuning parameter to switch on and off the topological nature of the material. Typically, this is done by chemical doping or thermal lattice expansion. However, chemical doping requires intensive work and can additionally change other factors of the material beyond the topology, and thermal lattice expansion prohibits studying both topological phases at low temperatures.In this work, I show that in-situ strain can be used to control the topological phase of ZrTe5. This strain can be easily controlled at temperatures ranging from 2K to room temperature and in magnetic fields, providing an ideal tuning parameter. Additionally, I uncover anomalous transport behavior such as an anomalous Hall effect and the magic angle effect in ultra-pure, high mobility ZrTe5 crystals. Such unique behavior originates in ZrTe5 due to its simplistic band structure, where electronic transport is dominated by highly mobile, topologically nontrivial bands at the Γ point. Because of this simplistic band structure and easily accessible tuning parameter, this work establishes ZrTe5 as a paradigm for further electronic transport studies, where strain can be used as a tool to further understand the importance of topology as it relates to these anomalous behaviors.