title: Semiclassical ordering in the large-N pyrochlore antiferromagnet.
abstract: We study the semiclassical limit of the Sp(N) generalization of the pyrochlore lattice Heisenberg antiferromagnet by expanding about the N --> infinity 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.
authors.affiliation: Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853-2501, USA. uh22@cornell.edu
authors.forename: U
authors.initials: U
authors.lastname: Hizi
authors.forename: Prashant
authors.initials: P
authors.lastname: Sharma
authors.forename: C L
authors.initials: CL
authors.lastname: Henley