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Semiclassical ordering in the large-N pyrochlore antiferromagnet

U. Hizi·Prashant Sharma·C. L. Henley
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Abstract

We study the semiclassical limit of the $Sp(N)$ generalization of the pyrochlore lattice Heisenberg antiferromagnet by expanding about the $N \to \infty$ saddlepoint in powers of a generalized inverse spin. To leading order, we write down an effective Hamiltonian as a series in loops on the lattice. Using this as a formula for calculating the energy of any classical ground state, we perform Monte-Carlo simulations and find a unique collinear ground state. This state is not a ground state of linear spin-wave theory, and can therefore not be a physical (N=1) semiclassical ground state.

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U. Hizi, Prashant Sharma, C. L. Henley. 2005-10-12. Semiclassical ordering in the large-N pyrochlore antiferromagnet. https://doi.org/10.1103/physrevlett.95.167203

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