Heterobilayer moir\'e magnets: moir\'e skyrmions and the commensurate-incommensurate transition

TL;DR

This paper investigates heterobilayer moiré magnets, revealing a rich phase diagram with various commensurate phases, including a skyrmion lattice, driven by inter-layer interactions and moiré patterns using theoretical and numerical methods.

Contribution

It introduces a comprehensive phase diagram for heterobilayer moiré magnets, highlighting the emergence of skyrmion lattices and the commensurate-incommensurate transition.

Findings

Identification of multiple moiré-periodic phases

Discovery of a skyrmion lattice phase within the moiré pattern

Analysis of the transition between commensurate and incommensurate states

Abstract

We study untwisted heterobilayers of ferromagnetic and antiferromagnetic van der Waals materials, with in particular a Dzyaloshinskii-Moriya interaction in the ferromagnetic layer. A continuum low energy field theory is utilized to study such systems. We develop a phase diagram as a function of the strength of inter-layer exchange and Dzyaloshinskii-Moriya interactions, combining perturbative and strong coupling analyses with numerical simulations using Landau-Lifshitz-Gilbert equations. Various moir\'e-periodic commensurate phases are found, and the commensurate-incommensurate transition is discussed. Among the commensurate phases, we observe an interesting skyrmion lattice phase wherein each moir\'e unit cell hosts one skyrmion.