Theoretical simulation of the anisotropic phases of antiferromagnetic thin films

TL;DR

This paper presents a comprehensive simulation of antiferromagnetic thin films, exploring how various interactions and anisotropies influence phase behavior, spin reorientation, and phase transformations across different film thicknesses and parameters.

Contribution

It introduces a unified phase diagram for all n-layer films and bulk systems, revealing layer-dependent spin reorientation and phase transformation mechanisms.

Findings

Anisotropy strength varies with layers, J, and n.

Unified phase diagram for all n-layer films and bulk.

Layer-dependent spin reorientation phase.

Abstract

We simulate antiferromagnetic thin films. Dipole-dipole and antiferromagnetic exchange interactions as well as uniaxial and quadrupolar anisotropies are taken into account. Various phases unfold as the corresponding parameters, J, D and C, as well as the temperature T and the number n of film layers vary. We find (1) how the strength Delta_m of the anisotropy arising from dipole-dipole interactions varies with the number of layers m away from the film's surface, with J and with n; (2) a unified phase diagram for all n-layer films and bulk systems; (3) a layer dependent spin reorientation (SR) phase in which spins rotate continuously as T, D, C and n vary; (4) that the ratio of the SR to the ordering temperature depends (approximately) on n only through (D+Delta/n)/C, and hardly on J; (5) a phase transformation between two different magnetic orderings, in which spin orientations may or may not change, for some values of J, by varying n.