Domain Wall in a Quantum Anomalous Hall Insulator as a Magnetoelectric Piston

TL;DR

This paper proposes a theoretical model where a domain wall in a quantum anomalous Hall insulator acts as a magnetoelectric piston, enabling efficient electrical control of domain walls for memory and logic devices.

Contribution

It introduces the concept of a magnetoelectric piston using a domain wall in a quantum anomalous Hall insulator and quantifies its efficiency with a universal effective spin-Hall angle.

Findings

Domain wall pumps charge current in a closed circuit.

Electrical bias induces reciprocal domain-wall motion.

Effective spin-Hall angle approaches a universal value of 2.

Abstract

We theoretically study the magnetoelectric coupling in a quantum anomalous Hall insulator state induced by interfacing a dynamic magnetization texture to a topological insulator. In particular, we propose that the quantum anomalous Hall insulator with a magnetic configuration of a domain wall, when contacted by electrical reservoirs, acts as a magnetoelectric piston. A moving domain wall pumps charge current between electrical leads in a closed circuit, while applying an electrical bias induces reciprocal domain-wall motion. This piston-like action is enabled by a finite reflection of charge carriers via chiral modes imprinted by the domain wall. Moreover, we find that, when compared with the recently discovered spin-orbit torque-induced domain-wall motion in heavy metals, the reflection coefficient plays the role of an effective spin-Hall angle governing the efficiency of the proposed electrical control of domain walls. Quantitatively, this effective spin-Hall angle is found to approach a universal value of $2$, providing an efficient scheme to reconfigure the domain-wall chiral interconnects for possible memory and logic applications.