Some Considerations on the Magnetic Carriers in Ferromagnetic Transition Metals

Abstract

Some properties of itinerant electron ferromagnets are examined theoretically on the basis of a simple model in which the electron Coulomb interaction is assumed to be effective only in an atomic cell. Results of our previous study on the neutron diffraction phenomena are briefly reviewed. An itinerant electron model seems to be capable of accounting for almost all features such as diffuse scattering, critical scattering, and paramagnetic scattering. It is emphasized that the spin-wave modes play very important roles. The study is extended to the low-temperature behavior of spin waves. Unlike the spin waves in a Heisenberg model, the spin-wave frequency in metallic ferromagnets has a T2 term in its temperature dependence. This is shown by a phenomenological consideration and also by explicit calculations on a s-d model and an itinerant electron model. Finally it is pointed out that the specific heat of the simple itinerant model has a singularity of (T-Tc)−½ around the Curie point.