Phase competition in frustrated anisotropic antiferromagnet in strong magnetic field

TL;DR

This paper theoretically investigates how small anisotropic interactions influence phase transitions in a frustrated antiferromagnet under strong magnetic fields, revealing complex phase competition and sequences.

Contribution

It provides analytical expressions for critical fields and ground-state energies, elucidating the role of anisotropy and dipolar interactions in phase competition.

Findings

Different phase sequences depend on anisotropic interactions.

Analytical results agree with Monte-Carlo simulations.

Multiple phases such as canted, helical, and fan orders are identified.

Abstract

We discuss theoretically a frustrated Heisenberg antiferromagnet in magnetic field close to the saturation one. It is demonstrated that a small biaxial anisotropy and/or the magnetic dipolar interaction produce a delicate balance between phases with a commensurate canted, incommensurate helical (conical), and fan spin orderings. As a result, different sequences of phase transitions are realized depending on values of these small anisotropic interactions. We derive analytical expressions for critical fields and ground-state energies of the phases which are in a quantitative agreement with our and previous Monte-Carlo simulations.