Spatially anisotropic Heisenberg Kagome antiferromagnet

TL;DR

This paper explores the phase diagram of a spatially anisotropic Heisenberg kagome antiferromagnet, revealing various magnetic phases and their dependence on anisotropy and spin length, using a large N theoretical approach.

Contribution

It provides a detailed theoretical analysis of the ground states of an anisotropic kagome antiferromagnet using the Sp(N) large N limit, which is a novel approach for this model.

Findings

Rich phase diagram with ferrimagnetic, incommensurate, and decoupled chain phases.

Dependence of ground states on anisotropy and spin length.

Identification of various magnetic orderings in the model.

Abstract

In the search for spin-1/2 kagome antiferromagnets, the mineral volborthite has recently been the subject of experimental studies [Hiroi et al.,2001]. It has been suggested that the magnetic properties of this material are described by a spin-1/2 Heisenberg model on the kagome lattice with spatially anisotropic exchange couplings. We report on investigations of the Sp(N) symmetric generalisation of this model in the large N limit. We obtain a detailed description of the dependence of possible ground states on the anisotropy and on the spin length S. A fairly rich phase diagram with a ferrimagnetic phase, incommensurate phases with and without long range order and a decoupled chain phase emerges.