A Dzyaloshinskii-Moriya Anisotropy in Nanomagnets with in-plane Magnetization

TL;DR

This paper reveals a new in-plane anisotropy in nanomagnets caused by Dzyaloshinskii-Moriya interaction, which depends on shape and can counteract demagnetization anisotropy in small, elongated magnets.

Contribution

It introduces a novel shape-dependent in-plane anisotropy arising from DMI, supported by experimental, numerical, and analytical evidence.

Findings

DMI induces an out-of-plane spin tilt at edges.

This tilt reduces DMI energy, affecting anisotropy.

The effect can counteract shape anisotropy in small magnets.

Abstract

We report on a new source of in-plane anisotropy in nanomagnets due to the presence of Dzyaloshinskii-Moriya interaction (DMI). This anisotropy depends on the shape of the magnet, and is orthogonal to the demagnetization shape anisotropy. This effect originates from the DMI energy reduction due to an out-of-plane tilt of the spins at edges oriented perpendicular to the magnetization. Our investigation combining experimental, numerical and analytical results demonstrate that this energy reduction can compensate the demagnetization shape anisotropy energy in magnets of elongated shape, provided that their volumes is small enough and thus that their magnetization is quasi-uniform.