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The energies and eigenvectors for long-wavelength acoustic spin waves in yttrium iron garnet are calculated neglecting spin-wave interactions, but including the effects of anisotropy and dipolar interactions. The sublattice magnetization is found to be Sαz(T)=S−δα−cT−AαT3/2−BαT5/2−CαT7/2⋯. Here α labels the sublattice a or d, δα expresses the effect of zero-point motion, and cT is the Holstein-Primakoff correction for dipolar interactions. Expressions in terms of the exchange integrals Jaa, Jdd, Jad, and Jad′, where Jad′ describes interactions between next-nearest-neighbor a and d sites, are given for Aα, Bα, and, when Jad′=0, for Cα. The spin-wave spectrum of some substituted garnets and the effect of spin-wave interactions on the zero-point disordering are treated in appendices.
Harris, A. (1967). Sublattice Magnetization of Yttrium Iron Garnet at Low Temperatures. Physical Review, 155 (2), 499-510. http://dx.doi.org/10.1103/PhysRev.155.499
Date Posted: 12 August 2015
This document has been peer reviewed.