Exchange Interactions in Rare-Earth-Transition Metal Compounds

The band structure calculations were made for RMn compounds, where R is a rare-earth element, M = Fe and Co, and n = 2, 3, 23/6 and 17/2. For each series, the magnetic moments of the transition metals linearly depend on the de Gennes factor with rates determined by their local environment. Exchange interactions are analyzed starting with the 4f–5d–3d model. The contributions of local 4f–5d interactions, as well as 5d–3d short-range interactions, to the polarization M5d of R5d band is determined. Exchange interactions at unit cell level are interdependent and mediated by the R5d band polarization. A linear dependence of the Curie temperatures on the M5d values is shown for each RMn series. The results are discussed in correlation with the experimental data obtained by magnetic and neutron diffraction measurements.