Giant $c$-axis nonlinear anomalous Hall effect in T$_d$-MoTe$_2$ and WTe$_2$

TL;DR

This paper reports a large nonlinear anomalous Hall effect along the c-axis in non-centrosymmetric T$_d$-MoTe$_2$ and WTe$_2$, driven by skew-scattering mechanisms, without magnetic order.

Contribution

It demonstrates an exceptionally large nonlinear anomalous Hall effect in T$_d$-MoTe$_2$ and WTe$_2$, highlighting the role of skew-scattering in non-magnetic materials.

Findings

Large Hall ratio of 2.47 under high bias

Anomalous Hall conductivity of approximately 8×10^7 S/m

Effect dominated by skew-scattering at high temperatures

Abstract

While the anomalous Hall effect can manifest even without an external magnetic field, time reversal symmetry is nonetheless still broken by the internal magnetization of the sample. Recently, it has been shown that certain materials without an inversion center allow for a nonlinear type of anomalous Hall effect whilst retaining time reversal symmetry. The effect may arise from either Berry curvature or through various asymmetric scattering mechanisms. Here, we report the observation of an extremely large $c$-axis nonlinear anomalous Hall effect in the non-centrosymmetric T$_d$ phase of MoTe$_2$ and WTe$_2$ without intrinsic magnetic order. We find that the effect is dominated by skew-scattering at higher temperatures combined with another scattering process active at low temperatures. Application of higher bias yields an extremely large Hall ratio of $E_\perp /E_\parallel$=2.47 and corresponding anomalous Hall conductivity of order 8x10$^7$S/m.