A Green Function Theory of Ferromagnetic Relaxation

概要

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Ferromagnetic relaxation due to the dipolar interaction is investigated in terms of the two-time Green function, adopting the decomposition procedure proposed in the previous papers. A general expression for the dipolar broadening, which is applicable to the whole range of temperature, is obtained. At low temperatures the width is treated in the form of a decay constant of a quasi-particle, which has a temperature dependent spectrum. Under the presence of degeneracy in the spectrum the decay constant of the uniform mode is calculated and the result is discussed with particular reference to its dependence on temperature and on the sample shape. Several remaining terms, which are negligible at low temperature and yet become important at higher temperature, are also discussed in order to understand the nature of the approximations involved in the present calculation. A qualitative discussion of the damping constant in the neighbourhood of the critical point is given, although the actual calculation is beyond the scope of the present work.
理論物理学刊行会の論文
1964-02-25