Twelve sublattice ordered phase in the J1-J2 model on the kagome lattice
Abstract
Motivated by recent experiments on an S=1/2 antiferromagnet on the kagome lattice, we investigate the Heisenberg J1-J2 model with ferromagnetic J1 and antiferromagnetic J2. Classically the ground state displays Neel long range order with 12 non-coplanar sublattices. The order parameter has the symmetry of a cuboctahedron so that it fully breaks SO(3) as well as the spin-flip symmetry, and we expect from the latter a Z2 symmetry breaking pattern. As might be expected from the Mermin-Wagner theorem in two dimensions, the SO(3) symmetry is restored by thermal fluctuations while the Z2 symmetry breaking persists up to a finite temperature. A complete study of S=1/2 exact spectra reveals that the classical order subsists for quantum spins in a finite range of parameters. First order spin wave calculations give the range of existence of this phase and the renormalisations at T=0 of the order parameters associated to both symmetry breakings. This phase is destroyed by quantum fluctuations for a small but finite J2/|J1|\simeq3 consistently with exact spectra studies which indicate a gapped phase.
Keywords
Cite
@article{arxiv.cond-mat/0502414,
title = {Twelve sublattice ordered phase in the J1-J2 model on the kagome lattice},
author = {Jean-Christophe Domenge and Philippe Sindzingre and Claire Lhuillier and Laurent Pierre},
journal= {arXiv preprint arXiv:cond-mat/0502414},
year = {2007}
}
Comments
Accepted for publication in Phys. Rev. B (2005)