Magnetic properties and electronic structures of R-Ni-B compounds where R is a heavy rare earth.

Magnetic measurements were performed in the temperature range 4.2–300 K and fields up to 70 kOe on R3Ni7B2 compounds with R = Gd, Tb, Dy, Ho, Er. The Curie temperatures decrease from 38.5 K (Gd) to 7 K (Er). Band structure calculations show that nickel, at 0 K, has a very small magnetic polarization, oriented antiparallel to the rare-earth moment. The XPS measurements suggest the presence of unoccupied Ni3d states. The reciprocal susceptibilities follow a Curie–Weiss type behaviour. Effective nickel moments of 1.33 ± 0.25 µB were determined. The magnetic behaviour of nickel is analysed in models which take into account electron correlation effects in d bands.