The Thermodynamics of Ferromagnets
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The discussion in Chap. 8 showed that the Heisenberg model provides a good description of the ordering of magnetic moments in a magnetic material, especially in the case of insulating compounds. However, this discussion considered only the properties of the ground state, so it cannot inform as to the thermodynamic properties of magnetic materials. This will be the task of the present chapter. We begin by discussing the low energy excited states in the Heisenberg model and deduce some low temperature properties. We shall then examine the vicinity of the critical temperature where an alternative approach will be needed, based on the molecular field theory.
KeywordsCurie Temperature Critical Exponent Spin Wave Heisenberg Model Spontaneous Magnetisation
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