Thermodynamic signatures for the existence of Dirac electrons in ZrTe5

TL;DR

This study uses various magnetic and transport measurements to identify thermodynamic signatures indicating the presence of Dirac electrons in ZrTe5, revealing complex electronic behavior and temperature-dependent transitions.

Contribution

It provides experimental evidence of Dirac semi-metallic behavior in ZrTe5 through thermodynamic signatures and explores temperature effects on its electronic structure.

Findings

Magnetization reversal from paramagnetic to diamagnetic beyond the quantum limit

Non-linearity in magnetization indicating additional low-energy carriers

Temperature sensitivity suggesting a Lifshitz transition

Abstract

We combine transport, magnetization, and torque magnetometry measurements to investigate the electronic structure of ZrTe5 and its evolution with temperature. At fields beyond the quantum limit, we observe a magnetization reversal from paramagnetic to diamagnetic response, which is characteristic of a Dirac semi-metal. We also observe a strong non-linearity in the magnetization that suggests the presence of additional low-lying carriers from other low-energy bands. Finally, we observe a striking sensitivity of the magnetic reversal to temperature that is not readily explained by simple band-structure models, but may be connected to a temperature dependent Lifshitz transition proposed to exist in this material.