Phase diagram and magnons in quasi-one-dimensional dipolar antiferromagnets

TL;DR

This paper explores the phase diagram and magnon excitations in quasi-one-dimensional dipolar antiferromagnets, highlighting the significance of dipolar interactions in determining magnetic phases and anisotropy.

Contribution

It provides a detailed analysis of how dipolar interactions influence phase stability and magnon spectra in antiferromagnetic spin chains on a hexagonal lattice.

Findings

Identification of multiple commensurate and incommensurate phases

Good agreement with experimental energy gaps in Mn-compounds

Dipolar interaction as key source of anisotropy

Abstract

We investigate antiferromagnetic spin chains, which are coupled by a weak antiferromagnetic exchange interaction on a hexagonal lattice. We particulary study the role of the dipole-dipole interaction within the framework of a Heisenberg model with nearest-neighbor exchange and additional dipolar interaction. We find several commensurate and incommensurate phases depending on the ratio of dipolar energy to interchain-exchange energy due to their competing qualtity. The ground-state analysis is supplemented by a stability analysis by means of a linear spin-wave theory. In comparison with experiments (CsMnBr_3, RbMnBr_3) we obtain good agreement for the energy gaps. From this we conclude, that the dipolar interaction is the most important source of anisotropy in these Mn-compounds.