Inhomogeneous States in a Small Magnetic Disk with Single-Ion Surface Anisotropy

TL;DR

This paper analyzes the ground and metastable states of easy-plane Heisenberg magnets in a disk with surface anisotropy, providing analytical descriptions and exploring the effects of lattice pinning.

Contribution

It offers a new analytical framework for understanding spin configurations in magnetic disks with surface anisotropy, including metastable states and lattice pinning effects.

Findings

Half-vortex configurations are preferred at strong anisotropy.

Analytical descriptions cover all anisotropy values.

Lattice pinning induces metastable configurations.

Abstract

We investigate analytically and numerically the ground and metastable states for easy-plane Heisenberg magnets with single-ion surface anisotropy and disk geometry. The configurations with two half-vortices at the opposite points of the border are shown to be preferable for strong anisotropy. We propose a simple analytical description of the spin configurations for all values of a surface anisotropy. The effects of lattice pinning leads to appearance of a set of metastable configurations.