Electrically tuneable nonlinear anomalous Hall effect in two-dimensional transition-metal dichalcogenides WTe2 and MoTe2

TL;DR

This study demonstrates a strong, tunable nonlinear anomalous Hall effect in monolayer WTe2 and MoTe2, driven by Berry curvature and controllable via electric fields, revealing potential for novel nonlinear phenomena in 2D materials.

Contribution

It reveals the electric-field tunability of the nonlinear anomalous Hall effect in 2D TMDs, linking topological phase transitions to Hall response.

Findings

Strong NLAHE observed in WTe2 and MoTe2 monolayers

NLAHE magnitude increases and reverses sign at topological transition

NLAHE can be tuned by out-of-plane electric field

Abstract

We studied the nonlinear electric response in WTe2 and MoTe2 monolayers. When the inversion symmetry is breaking but the the time-reversal symmetry is preserved, a second-order Hall effect called the nonlinear anomalous Hall effect (NLAHE) emerges owing to the nonzero Berry curvature on the nonequilibrium Fermi surface. We reveal a strong NLAHE with a Hall-voltage that is quadratic with respect to the longitudinal current. The optimal current direction is normal to the mirror plane in these two-dimensional (2D) materials. The NLAHE can be sensitively tuned by an out-of-plane electric field, which induces a transition from a topological insulator to a normal insulator. Crossing the critical transition point, the magnitude of the NLAHE increases, and its sign is reversed. Our work paves the way to discover exotic nonlinear phenomena in inversion-symmetry-breaking 2D materials.