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A Study of Spin–Phonon Interactions in Ferromagnetic Insulators. I. The Spin Wave Spectrum
Author(s) -
Jones M. J.,
Cottam M. G.
Publication year - 1974
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.2220660229
Subject(s) - condensed matter physics , spin wave , physics , phonon , ferromagnetism , spins , spin (aerodynamics) , spin polarization , perturbation theory (quantum mechanics) , heisenberg model , magnon , wave vector , perturbation (astronomy) , quantum mechanics , electron , thermodynamics
Abstract A field‐theoretical perturbation method is used to study the effects of Spin–phonon interactions in a Heisenberg ferromagnet. The calculations are carried out by employing an expansion in powers of the high‐density parameter 1/z, where z is the number of spins interacting with any given spin. In lowest order (1/z) 0 this leads to molecular field theory, and the effects of spin fluctuations and Spin–phonon interactions are then introduced in higher orders of the perturbation expansion. The renormalised energy and damping of the spin wave excitations are evaluated to second order in the Spin–phonon coupling, and the dependence of these quantities on temperature, wave vector, and magnetic field is obtained. The calculations are valid over a wide range of temperature below T c .