Monte Carlo Studies on Geometrically Confined Skyrmions in Nanodots: Stability and Morphology under Radial Stresses

TL;DR

This study uses Finsler geometry modeling to numerically analyze how radial stresses influence the stability and shape of skyrmions in nanodots, revealing stress-induced effects on skyrmion morphology and stability.

Contribution

It introduces a Finsler geometry-based numerical approach to model stress effects on skyrmions in nanodots, highlighting the role of radial stresses in skyrmion stability and morphology.

Findings

Radial stresses enhance surface effects stabilizing skyrmions.

Tensile stress leads to incomplete skyrmions at the center.

Compressive stress results in target skyrmions.

Abstract

We numerically study the stability and morphology of geometrically confined skyrmions in nanodots using Finsler geometry (FG) modeling technique. The FG model dynamically implements anisotropies in ferromagnetic interaction, Dzyaloshinskii-Moriya interaction, and magneto-elastic coupling in response to mechanical stresses. Without the stresses, there exists a geometrically confined effect originating from the surface effect of small nanodots, in which skyrmions are stabilized under a low external magnetic field. This surface effect is enhanced by radial stresses, which significantly reduce the surface DMI compared to the bulk DMI. The radial stresses also alter the interactions to be anisotropic. Owing to these position- and direction-dependent interactions, incomplete skyrmions emerge at the center of the nanodots under the tensile stress. In addition to the incomplete skyrmions, target skyrmions are observed under the compressive stress. Our numerical results indicate that the strain-enhanced surface effect and the strain-induced interaction anisotropies suitably explain the skyrmion stability in nanodots with zero magnetic field.