Critical dynamics of a uniaxial and dipolar ferromagnet
We study the critical dynamics of three-dimensional ferromagnets with uniaxial anisotropy by taking into account exchange and dipole-dipole interaction. The dynamic spin correlation functions and the transport coefficients are calculated within a mode coupling theory. It is found that the crossover scenario is determined by the subtle interplay between three length scales: the correlation length, the dipolar and uniaxial wave vector. We compare our theoretical findings with hyperfine interaction experiments on Gd and find quantitative agreement. This analysis allows us to identify the universality class for Gd. It also turns out that the µSR relaxation rate can be best fitted if it is assumed that muons occupy octahedral interstitials sites within the Gd lattice.
In this paper a rigorous mathematical analysis of a synchronous machine with solid cylindrical rotor is presented. The analysis embodies a departure from the usual method of considering machine performance by means of circuit theory, and presents an attack from the point of view of field-distribution theory. Such an analysis is desirable, for it provides a definite means of considering the effect of eddy currents in the solid iron rotor.