Domain structures in ultrathin magnetic films

TL;DR

This paper investigates the formation and characteristics of magnetic domain structures in ultrathin films, considering various spin models and temperature effects, revealing complex phase behaviors and domain wall dynamics.

Contribution

It provides a detailed analysis of domain structures in ultrathin magnetic films, including the effects of anisotropy, spin models, and temperature on magnetic ground states and domain configurations.

Findings

Domains form when perpendicular anisotropy exceeds shape anisotropy.

Reorientation phase transition occurs in Heisenberg spin models.

Finite temperature domain walls behave like a liquid crystal.

Abstract

Domain structures appear in ultrathin magnetic films, if an easy-axis anisotropy, favouring the direction perpendicular to the film, overcomes the shape anisotropy. We will study the nature of the magnetic ground state and how the different parameters influence the domain structure. Both Ising and Heisenberg spins will be considered: in the latter case, a reorientation phase transition may take place. Domains are expected to appear just before such transition. Domain structures at finite temperature will be described in terms of a two dimensional array of domain walls, whose behaviour resembles a liquid crystal.