Magneto-transport evidence for strong topological insulator phase in ZrTe5

TL;DR

This study demonstrates that band inversion can be identified through magneto-transport measurements, providing a practical method to detect topological phases in narrow-gap materials like ZrTe5.

Contribution

The paper introduces a new experimental approach using Landau level splitting to identify band inversion and topological phases in narrow-gap topological insulators.

Findings

Observation of four-fold Landau level splitting in ZrTe5

Detection of additional quantum oscillation splittings

Identification of an anomalous peak in the quantum limit

Abstract

The identification of a non-trivial band topology usually relies on directly probing the protected surface/edge states. But, it is difficult to achieve electronically in narrow-gap topological materials due to the small (meV) energy scales. Here, we demonstrate that band inversion, a crucial ingredient of the non-trivial band topology, can serve as an alternative, experimentally accessible indicator. We show that an inverted band can lead to a four-fold splitting of the non-zero Landau levels, contrasting the two-fold splitting (spin splitting only) in the normal band. We confirm our predictions in magneto-transport experiments on a narrow-gap strong topological insulator, zirconium pentatelluride (ZrTe$_5$), with the observation of additional splittings in the quantum oscillations and also an anomalous peak in the extreme quantum limit. Our work establishes an effective strategy for identifying the band inversion as well as the associated topological phases for future topological materials research.