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Twelve sublattice ordered phase in the J1-J2 model on the kagome lattice

Jean-Christophe Domenge·Philippe Sindzingre·Claire Lhuillier·Laurent Pierre
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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.

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Jean-Christophe Domenge, Philippe Sindzingre, Claire Lhuillier, Laurent Pierre. 2005-07-05. Twelve sublattice ordered phase in the J1-J2 model on the kagome lattice. https://doi.org/10.1103/physrevb.72.024433

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