Degenerate perturbation theory of quantum fluctuations in a pyrochlore antiferromagnet

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dc.creatorBergman, Doron L.
dc.creatorShindou, Ryuichi
dc.creatorFiete, Gregory A.
dc.creatorBalents, Leon
dc.date2006-07-07
dc.date.accessioned2026-07-07T07:53:34Z
dc.date.available2026-07-07T07:53:34Z
dc.descriptionWe study the effect of quantum fluctuations on the half-polarized magnetization plateau of a pyrochlore antiferromagnet. We argue that an expansion around the easy axis limit is appropriate for discussing the ground state selection amongst the classically degenerate manifold of collinear states with a 3:1 ratio of spins parallel/anti-parallel to the magnetization axis. A general approach to the necessary degenerate perturbation theory is presented, and an effective quantum dimer model within this degenerate manifold is derived for arbitrary spin $s$. We also generalize the existing semiclassical analysis of Hizi and Henley [Phys. Rev. B {\bf 73}, 054403 (2006)] to the easy axis limit, and show that both approaches agree at large $s$. We show that under rather general conditions, the first non-constant terms in the effective Hamiltonian for $s\geq 1$ occur only at {\sl sixth} order in the transverse exchange coupling. For $s\geq 3/2$, the effective Hamiltonian predicts a magnetically ordered state. For $s\leq 1$ more exotic possibilities may be realized, though an analytical solution of the resulting quantum dimer model is not possible.
dc.identifierhttps://arxiv.org/abs/cond-mat/0607210
dc.identifierhttp://arxiv.org/abs/cond-mat/0607210
dc.identifierPhys. Rev. B 75, 094403 (2007) (31 pages)
dc.identifierdoi:10.1103/PhysRevB.75.094403
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/126270
dc.subjectStrongly Correlated Electrons
dc.titleDegenerate perturbation theory of quantum fluctuations in a pyrochlore antiferromagnet
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