Giant nonlinear Hall effect in twisted bilayer WTe2

Zhihai He,Hongming Weng

doi:10.1038/s41535-021-00403-9

Abstract

In a system with broken inversion symmetry, a second-order nonlinear Hall effect can survive even in the presence of time-reversal symmetry. In this work, we show that a giant nonlinear Hall effect can exist in twisted bilayer WTe2 system. The Berry curvature dipole of twisted bilayer WTe2 (θ = 29.4°) can reach up to ~1400 Å, which is much larger than that in previously reported nonlinear Hall systems. In twisted bilayer WTe2 system, there exist abundant band anticrossings and band inversions around the Fermi level, which brings a complicated distribution of Berry curvature, and leads to the nonlinear Hall signals that exhibit dramatically oscillating behavior in this system. Its large amplitude and high tunability indicate that the twisted bilayer WTe2 can be an excellent platform for studying the nonlinear Hall effect.

Highlights

Over the last few decades, the study of various Hall effects has become an important topic in condensed-matter physics
We focus on the nonlinear Hall effect in twisted bilayer WTe2 with twist angle θ = 29.4°
We calculate the energy dependence of Berry curvature dipole for twisted bilayer WTe2 with twist angle θ = 40.1°, the results are shown in Supplementary Fig. 3a

Summary

Introduction

Over the last few decades, the study of various Hall effects has become an important topic in condensed-matter physics. A recent theoretical study predicted that a second-order nonlinear Hall effect can exist in materials with time-reversal symmetry but without inversion symmetry[2]. Multiple materials[5,6,7,8,9,10,11,12,13,14,15,16,17] have been predicted or validated to possess strong nonlinear Hall effect, such as the Weyl semimetals[5,6,7,8], the giant Rashba material bismuth tellurium iodine (BiTeI) under pressure[10], the monolayer WTe2 and MoTe2 with an external electric field[11], and the strained twisted bilayer graphene[12] or WSe213,14

Methods

Results

Conclusion