Quantum fluctuations stabilize Skyrmion textures

TL;DR

Quantum spin fluctuations generate Casimir-like magnetic fields that can stabilize skyrmion textures, with these effects contributing significantly to the energy landscape and potentially being experimentally observable.

Contribution

This work demonstrates that quantum zero point energy induces Casimir-like fields that influence skyrmion stability, a novel quantum effect in magnetic textures.

Findings

Casimir magnetic fields contribute about 10% of Zeeman energy needed to annihilate skyrmions.

Quantum fluctuations can stabilize skyrmions against external magnetic fields.

The effect is observable and significant in the energy balance of skyrmion textures.

Abstract

Here we show that the zero point energy associated to the quantum spin fluctuations of a non- collinear spin texture produce Casimir-like magnetic fields. We study the effect of these Casimir fields on the topologically protected non-collinear spin textures known as skyrmions. We calculate the zero point energy, to the lowest order in the spin wave expansion, in a Heisenberg model with Dzyalonshinkii-Moriya interactions chosen so that the classical ground state displays skyrmion textures, that disappear upon application of a strong enough magnetic field. Our calculations show that the Casimir magnetic field contributes a 10 percent of the total Zeeman energy necessary to delete the skyrmion texture with an applied field, and is thereby an observable effect.