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arXiv · 0902.2922

Magnetic field induced semimetal-to-canted-antiferromagnet transition on the honeycomb lattice

M. Bercx·T. C. Lang·F. F. Assaad
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Abstract

It is shown that the semimetallic state of the two-dimensional honeycomb lattice with a point-like Fermi surface is unstable towards a canted antiferromagnetic insulator upon application of an in-plane magnetic field. This instability is already present at the mean-field level; the magnetic field shifts the up- and the down-spin cones in opposite directions thereby generating a finite density of states at the Fermi surface and a perfect nesting between the up- and the down-spin Fermi sheets. This perfect nesting triggers a canted antiferromagnetic insulating state. Our conclusions, based on mean-field arguments, are confirmed by auxiliary field projective quantum Monte Carlo methods on lattices up to $12 \times 12$ unit cells.

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M. Bercx, T. C. Lang, F. F. Assaad. 2009-07-16. Magnetic field induced semimetal-to-canted-antiferromagnet transition on the honeycomb lattice. https://doi.org/10.1103/physrevb.80.045412

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