Magnetic proximity and nonreciprocal current switching in a monolayer WTe2 helical edge

TL;DR

This study demonstrates how stacking 2D materials like monolayer WTe2 and CrI3 can control edge conductance and induce nonreciprocal current switching through magnetic coupling, revealing new possibilities for 2D topological devices.

Contribution

It introduces a method to couple topological edge states with layered antiferromagnets, enabling magnetic control of edge conductance and nonreciprocal current in 2D heterostructures.

Findings

Edge conductance is sensitive to CrI3 magnetization state.

Coupling induces a gap in the helical edge states.

Large nonreciprocal current can be switched by magnetic state.

Abstract

The integration of diverse electronic phenomena, such as magnetism and nontrivial topology, into a single system is normally studied either by seeking materials that contain both ingredients, or by layered growth of contrasting materials. The ability to simply stack very different two dimensional (2D) van der Waals materials in intimate contact permits a different approach. Here we use this approach to couple the helical edges states in a 2D topological insulator, monolayer WTe2, to a 2D layered antiferromagnet, CrI3. We find that the edge conductance is sensitive to the magnetization state of the CrI3, and the coupling can be understood in terms of an exchange field from the nearest and next-nearest CrI3 layers that produces a gap in the helical edge. We also find that the nonlinear edge conductance depends on the magnetization of the nearest CrI3 layer relative to the current direction. At low temperatures this produces an extraordinarily large nonreciprocal current that is switched by changing the antiferromagnetic state of the CrI3.