Valley Magnetoelectricity in Single-Layer MoS2

TL;DR

This paper demonstrates a novel valley magnetoelectric effect in single-layer MoS2, where electric fields induce valley magnetization, promising for valleytronic applications at room temperature.

Contribution

It introduces a new valley-based magnetoelectric effect in 2D MoS2, achieved by symmetry breaking and electrical control, with experimental validation and theoretical modeling.

Findings

Electrical generation of valley magnetization in MoS2.

Magnetization is independent of in-plane magnetic fields.

Effect persists at room temperature.

Abstract

Magnetoelectric (ME) effect, the phenomenon of inducing magnetization by application of an electric field or vice versa, holds great promise for magnetic sensing and switching applications. Studies of the ME effect have so far focused on the control of the electron spin degree of freedom (DOF) in materials such as multiferroics and conventional semiconductors. Here, we report a new form of the ME effect based on the valley DOF in two-dimensional (2D) Dirac materials. By breaking the three-fold rotational symmetry in single-layer MoS2 via a uniaxial stress, we have demonstrated the pure electrical generation of valley magnetization in this material, and its direct imaging by Kerr rotation microscopy. The observed out-of-plane magnetization is independent of in-plane magnetic field, linearly proportional to the in-plane current density, and optimized when the current is orthogonal to the strain-induced piezoelectric field. These results are fully consistent with a theoretical model of valley magnetoelectricity driven by Berry curvature effects. Furthermore, the effect persists at room temperature, opening possibilities for practical valleytronic devices.