On the 4f-3d exchange interaction in intermetallic compounds

A review is given of the experimental values of the magnetic intersublattice-coupling constants in rare-earth (R) - transition-metal (T) intermetallics, derived from high-field magnetization measurements on single-crystalline powder particles that are free to be oriented by the applied magnetic field. The results are compared with values for the intersublattice-coupling constant obtained by other experimental methods and with results of electronic-band-structure calculations made for a few of the compounds investigated. An empirical relationship is found between the intersublattice-coupling constants and the reciprocal normalized molar volumes of the various R-T compounds, including T = Ni, Co and Fe.