Giant c-axis nonlinear anomalous Hall effect in Td-MoTe2 and WTe2

Archana Tiwari,Jahyun Koo,Shazhou Zhong,Qian Niu,Yuping Sun,Fangchu Chen,Austin Kaczmarek,Elizabeth Drueke,Cong Xiao,Xuan Luo,Liuyan Zhao,Jingjing Gao,Adam W Tsen,Binghai Yan

doi:10.1038/s41467-021-22343-5

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 Td phase of MoTe2 and WTe2 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⊥/E|| = 2.47 and corresponding anomalous Hall conductivity of order 8 × 107 S/m.

Highlights

While the anomalous Hall effect can manifest even without an external magnetic field, time reversal symmetry is still broken by the internal magnetization of the sample
While parsing the different contributions of the anomalous Hall effect (AHE) has been a grand challenge in condensed matter physics for many decades, the overall strength of the AHE can be clearly quantified by the Hall ratio
In non-centrosymmetric materials retaining time reversal symmetry, it is possible to realize a nonlinear AHE (NLAHE), whereby the current induces an effective magnetization in the sample and establishes a transverse electric field that increases quadratically with applied electric field[4,5,6,7,8,9,10,11,12]

Summary

Introduction

While the anomalous Hall effect can manifest even without an external magnetic field, time reversal symmetry is still broken by the internal magnetization of the sample. 1234567890():,; In ferromagnetic conductors, passage of charge current can generate an electric field in the transverse direction even without the application of an external magnetic field This anomalous Hall effect (AHE) requires broken time reversal symmetry and originates both from topological aspects of the material’s band structure and electron scattering coupled to the spin-orbit interaction[1]. The corresponding anomalous Hall (transverse) conductivity, ~8 ́ 107S=m, is the largest in any material These effects arise primarily from skew-scattering at higher temperatures combined with another scattering process at lower temperatures that increases the NLAHE strength exponentially with linear longitudinal conductivity. By performing measurements across different temperatures and sample thicknesses down to the

Methods

Results

Conclusion