Spectrum of short-wavelength magnons in two-dimensional quantum Heisenberg antiferromagnet on a square lattice: third order expansion in 1/S

A. V. Syromyatnikov

doi:10.1088/0953-8984/22/21/216003

paper

Spectrum of short-wavelength magnons in two-dimensional quantum Heisenberg antiferromagnet on a square lattice: third order expansion in 1/S

arXiv:1005.1568 · doi:10.1088/0953-8984/22/21/216003

Abstract

The spectrum of short-wavelength magnons in two-dimensional quantum Heisenberg antiferromagnet on a square lattice is calculated in the third order in $1/ S$ expansion. It is shown that $1/ S$ series for $S = 1/2$ converges fast in the whole Brillouin zone except for the neighborhood of the point $k = (π, 0)$ , at which absolute values of the third and the second order $1/ S$ -corrections are approximately equal to each other. It is shown that the third order corrections make deeper the roton-like local minimum at $k = (π, 0)$ improving the agreement with the recent experiments and numerical results in the neighborhood of this point. It is suggested that $1/ S$ series converges slowly near $k = (π, 0)$ also for $S = 1$ although the spectrum renormalization would be small in this case due to very small values of high-order $1/ S$ corrections.

11 pages, 2 figures

References in corpus (1)

Quantum dynamics and entanglement of spins on a square lattice

Spectrum of short-wavelength magnons in two-dimensional quantum Heisenberg antiferromagnet on a square lattice: third order expansion in 1/S

Abstract

References in corpus (1)

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