Curved Magnetism in CrI$_3$

TL;DR

This paper uses non-collinear-spin DFT to determine flexomagnetic coupling in monolayer CrI3, revealing how curvature influences magnetic states and highlighting the significant role of spin-orbit interactions in curved 2D magnets.

Contribution

It introduces a method to calculate flexomagnetic coefficients from first principles and applies it to CrI3, showing curvature-driven magnetic phase transitions and the importance of spin-orbit effects.

Findings

Crossover from normal to cycloidal magnetization with curvature

Large impact of spin-orbit interactions on curvature-induced anisotropy

Effective anisotropy and Dzyaloshinskii-Moriya contributions explain phase transition

Abstract

Curved magnets attract considerable interest for their unusually rich phase diagram, often encompassing exotic (e.g., topological or chiral) spin states. Micromagnetic simulations are playing a central role in the theoretical understanding of such phenomena; their predictive power, however, rests on the availability of reliable model parameters to describe a given material or nanostructure. Here we demonstrate how non-collinear-spin polarized density-functional theory can be used to determine the flexomagnetic coupling coefficients in real systems. By focusing on monolayer CrI$_3$, we find a crossover as a function of curvature between a magnetization normal to the surface to a cycloidal state, which we rationalize in terms of effective anisotropy and Dzyaloshinskii-Moriya contributions to the magnetic energy. Our results reveal an unexpectedly large impact of spin-orbit interactions on the curvature-induced anisotropy, which we discuss in the context of existing phenomenological models.