Surface spin-flop phases and bulk discommensurations in antiferromagnets

TL;DR

This paper investigates the phase diagrams of antiferromagnets with respect to anisotropy and magnetic field, revealing the existence of surface spin-flop phases, discommensurations, and their interplay, correcting previous misconceptions.

Contribution

It provides a detailed analysis of surface spin-flop phases and discommensurations in antiferromagnets, clarifying their distinctions and conditions for stability.

Findings

Surface spin-flop phase exists for all anisotropy values.

Divergence of penetration length indicates a transition region.

Discommensurations can replace surface reconstructions under certain conditions.

Abstract

Phase diagrams as a function of anisotropy D and magnetic field H are obtained for discommensurations and surface states for a model antiferromagnet in which $H$ is parallel to the easy axis. The surface spin-flop phase exists for all $D$. We show that there is a region where the penetration length of the surface spin-flop phase diverges. Introducing a discommensuration of even length then becomes preferable to reconstructing the surface. The results are used to clarify and correct previous studies in which discommensurations have been confused with genuine surface spin-flop states.