Experimental observation of anisotropic Adler-Bell-Jackiw anomaly in type-II Weyl semimetal WTe$_{1.98}$ crystals at the quasi-classical regime

TL;DR

This study experimentally observes the anisotropic Adler-Bell-Jackiw anomaly in WTe$_{1.98}$ crystals, revealing temperature-dependent topological phase transitions and anisotropic transport properties in type-II Weyl semimetals.

Contribution

It provides the first experimental evidence of anisotropic ABJ anomaly in WTe$_{1.98}$ and links it to topological phase transitions verified by first-principles calculations.

Findings

Anisotropic ABJ anomaly coefficients along a- and b-axis at 2 K.

Temperature-sensitive ABJ anomaly linked to topological phase transition.

Observation of anisotropic transport properties in the quasi-classical regime.

Abstract

The asymmetric electron dispersion in type-II Weyl semimetal theoretically hosts anisotropic transport properties. Here we observe the significant anisotropic Adler-Bell-Jackiw (ABJ) anomaly in the Fermi-level delicately adjusted WTe$_{1.98}$ crystals. Quantitatively, $C_w$ , a coefficient representing intensity of ABJ anomaly, along a- and b-axis of WTe$_{1.98}$ are 0.030 and 0.051 T$^{-2}$ at 2 K, respectively. We found that temperature-sensitive ABJ anomaly is attributed to topological phase transition from type-II Weyl semimetal to trivial semimetal, which is verified by first-principles calculation using experimentally determined lattice parameters at different temperatures. Theoretical electrical transport study reveals that observation of ansotropic ABJ both along a- and b-axis in WTe$_{1.98}$ is attributed to electrical transport in the quasi-classical regime. Our work may suggest that electron-doped WTe$_2$ is an ideal playground to explore the novel properties in type-II Weyl semimetals.