Giant Dzyaloshinskii-Moriya interaction and ratchet motion of bimeronic excitations in two-dimensional magnets

TL;DR

This paper demonstrates how giant Dzyaloshinskii-Moriya interaction in 2D magnets enables the formation and unidirectional motion of bimeronic excitations, advancing potential spintronic and memory device applications.

Contribution

It introduces a new compositional engineering method to induce giant DMI in 2D magnets and reveals the ratchet motion of bimeronic excitations.

Findings

Giant DMI achieved in CrMnI6 2D magnet via symmetry breaking.

Bimeronic excitations can be generated and exhibit unidirectional propagation.

Potential for racetrack memory applications with controlled topological excitations.

Abstract

Topological magnetic excitations rooted in Dzyaloshinskii-Moriya interaction (DMI) are promising information carriers for next-generation memory and spintronic devices. The recently discovered two-dimensional (2D) magnets provide fertile new platforms for revealing rich physical phenomena with atomic-scale precision, as exemplified by the enhanced DMI associated with an effective electric field that breaks the inversion symmetry. Here we use first-principles calculations to establish a conceptually difierent compositional engineering approach to induce giant DMI in a representative CrMnI$_6$ 2D magnet, and the underlying mechanism is rooted in the spontaneous inversion symmetry breaking in the bipartite system. Using atomistic magnetics simulations, we further reveal that bimeronic excitations can emerge upon cooling a spin random state or perturbing a ferromagnetic state. Strikingly, the bimeron can exhibit unidirectional soliton-like propagation, and such a ratchet phenomenon is highly desirable for racetrack memories. These findings may prove instrumental in developing novel devices for quantum information based on 2D magnets.