Thermomagnetic properties of rare-earth magnets

Multielectron spectra for rare-earth ferro- and ferrimagnets are calculated in linear approximation by the dynamic parts of angular momentum operators. Magnons are considered as dipole transitions between energy levels of rare-earth ions in crystal field broadened by interionic exchange interaction into the bands. Renormalization of the exchange stiffuess, temperature dependences of sublattice magnetizations and rare-earth contribution into ferrimagnet anisotropy constants are calculated. Comparisons with the experiment is carried out for R2F14B-type intermetallic compounds