Isotropic Spin Wave Theory of Short-Range Magnetic Order
arXiv:cond-mat/9602044 · doi:10.1103/PhysRevLett.76.4416
Abstract
We present an isotropic spin wave (ISW) theory of short-range order in Heisenberg magnets, and apply it to square lattice S=1/2 and S=1 antiferromagnets. Our theory has three identical (isotropic) spin wave modes, whereas the conventional spin wave theory has two transverse and one longitudinal mode. We calculate temperature dependences of various thermodynamic observables analytically and find good (several per cent) agreement with independently obtained numerical results in a broad temperature range.
4 pages, REVTeX v3 with 3 embedded PostScript figures