Magneto-transport evidence for strong topological insulator phase in ZrTe5

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 (ZrTe5), 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.

Ultrahigh Carrier Mobility in Cd3As2 Nanowires

“…Both curves show a semiconductor‐like behavior as the temperature is reduced (resistance increasing with decreasing temperature), similar to other DSMs, such as NaBi and ZrTe, attributed to a low carrier density. [ 34,35 ] The zero‐field cooled curve shows a metallic response close to 50 K which then flattens out below 20 K, while the field cooling result does not show any signs of a metallic behavior. As semimetals are gapless, carriers in the valence band may be deactivated thermally if the Fermi level is close to the DP as the temperature goes down.…”

Controllable strain-driven topological phase transition and dominant surface-state transport in HfTe5

“…The HfTe 5 layers are stacked together along the b- axis through van der Waals interactions to form a 3D layered crystal. The topological nature of as-grown samples has been debated, with different experiments finding that the pentatellurides can be either a weak topological insulator (WTI) 31 – 34 , a strong topological insulator (STI) 27 , 35 , 36 , or a Dirac semimetal (DSM) 26 , 37 – 39 . This inconsistency may be due to the pentatellurides ground state lying close to the phase boundary between a WTI and an STI phase 25 .…”

Superconductivity in single-crystalline ZrTe3−x (x ≤ 0.5) nanoplates

“…22 Massless Dirac fermions and negative magnetoresistance were observed in topological material candidate ZrTe 2 . 23–25 Although the topological nature of ZrTe 5 remains a puzzle, a number of interesting phenomena have been discovered in transport experiments, such as log-periodic oscillations, 26 the quantum Hall effect, 27 four-fold splitting of the non-zero Landau levels, 28 gigantic magneto-chiral anisotropy, 29 etc. Another fascinating composition is layered ZrTe 3 , which was known for decades as a CDW material.…”

“…In this case, T c is about 3.4 K, which is larger than that of bulk ZrTe 3 crystals. 28 Superconductivity transport of different samples can be seen from ESI Fig. S2–S5 †.…”