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Scattering of ferromagnetic band-electrons by phonons combined with the spin–orbit interaction is shown to cause magnetic relaxation of the Landau–Lifshitz–Gilbert type. Two formally distinct processes are simply analyzed: (a) spin-flip scattering of electrons and (b) ordinary scattering between spin-dependent band levels. Estimates of the magnitude of the damping constant λ are derived for both cases, which agree in orders of magnitude with the experimental values for Fe and Ni. Relations of direct and inverse proportionality between λ and the ordinary collision frequency are found in the cases (a) and (b), respectively.

Landau-Lifshitz-Looyenga's formula for correlation of bulk and powder dielectric parameters has been investigated at microwave and radio frequencies for a number of materials for wide enough experimental conditions of particle size, shape and packing fraction. It has been found that the formula gives good accuracy (about 3%) for dielectric constant determination for particle size not less than 50 μm. For fine powders (particle size less than 30 μm) the deduced dielectric constant is too low by about 3-8%. Dielectric loss determination from the formula is, however, less accurate, the deduced values being always too low by about 10-20%.

The difference between the Gilbert equation and the Landau-Lifshitz equation is discussed. An interpretation is presented that both equations assume viscous type damping, and the damping action is isotropic in the Gilbert equation, but is strongly anisotropic in the Landau-Lifshitz equation. It seems more reasonable to assume the Gilbert equation physically, if we do not know anything about the detailed mechanism of the damping of a problem.

A simple semiclassical theory of spin wave propagation in an amorphous Heisenberg ferromagnet is developed. The ferromagnet is assumed to consist of randomly distributed identical magnetic atoms. The discrete spin of the atoms is replaced by a function which varies continuously with position. The theory can be regarded as an extension of the Landau‐Lifshitz and Herring‐Kittel theory of spin waves in crystalline ferromagnets. It is found that both extended and localized spin waves may exist in these systems. The localized spin waves find their origin in the structural randomness. The possible effect that the localized spin waves may have on spin wave resonance is pointed out.

Two-point kinetic theory, along with double-series Hermite expansion, is shown to afford Landau-Lifshitz's fluctuation formulae in a most straightforward manner, i.e. without invoking random force terms or Markovian nature as in the existing theories.

The purpose of this letter is to propose a new microscopic derivation of the LandauLifshitz equation for ferromagnets1> which are used to study the motion of the Bloch wall and the ferromagnetic resonances. This is done by using a new method similar to Kawabata's recent derivation of a LandauLifshitz type equation for a spin interacting with its surroundings.2> Our derivation is more general than that of Callen which is limited to the spin-wave region.3> We consider an isotropic Heisenberg spin system whose exchange interaction is modulated by the thermal sound waves. Namely, we start with the following Hamiltonian

An equation of motion of magnetization in the Heisenberg antiferro-magnet has been derived using a non-equilibrium statistical operator.

The anomaly in the adiabatic compressibility at the Neel point of alpha manganese, as determined from ultrasonic measurements is quantitatively compared with the expected value derived from the Landau-Lifshitz theory of 2nd order transitions. Agreement is satisfactory.

The Bloch domain-wall equation of motion is immediately derived from the Landau-Lifshitz equation.