Diversity of states in a chiral magnet nanocylinder

TL;DR

This study explores the variety of magnetic states in a FeGe nanocylinder, revealing a stable dipole string spin texture influenced by surface damage, through combined experimental and micromagnetic simulation approaches.

Contribution

It demonstrates the stability of a dipole string spin texture in a confined nanocylinder and emphasizes the role of surface damage in magnetic state determination.

Findings

Observation of a stable dipole string spin texture.

Quantitative agreement between experiment and simulation.

Surface damage significantly affects magnetic states.

Abstract

The diversity of three-dimensional magnetic states in a FeGe nanocylinder is studied using micromagnetic simulations and off-axis electron holography in the transmission electron microscope. In particular, we report the observation of a dipole string -- a spin texture composed of two coupled Bloch points -- which becomes stable under geometrical confinement. Quantitative agreement is obtained between experimental and theoretical phase shift images by taking into account the presence of a damaged layer on the surface of the nanocylinder. The theoretical model is based on the assumption that the damaged surface layer, which results from focused ion beam milling during sample preparation, has similar magnetic properties to those of an amorphous FeGe alloy. The results highlight the importance of considering the magnetic properties of the surface layers of such nanoscale samples, which influence their magnetic states.