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arXiv · cond-mat/9402044

Spiral Magnets as Gapless Mott Insulators

R. Cote·A. -M. S. Tremblay
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Abstract

In the large $U$ limit, the ground state of the half-filled, nearest-neighbor Hubbard model on the triangular lattice is the three-sublattice antiferromagnet. In sharp contrast with the square-lattice case, where transverse spin-waves and charge excitations remain decoupled to all orders in $t/U$, it is shown that beyond leading order in $t/U$ the three Goldstone modes on the triangular lattice are a linear combination of spin and charge. This leads to non-vanishing conductivity at any finite frequency, even though the magnet remains insulating at zero frequency. More generally, non-collinear spin order should lead to such gapless insulating behavior.

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R. Cote, A. -M. S. Tremblay. 1994-02-09. Spiral Magnets as Gapless Mott Insulators. https://doi.org/10.1209/0295-5075%2F29%2F1%2F007

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