Ferrimagnetism of the Rare-Earth-Cobalt Intermetallic Compounds R2Co17

Abstract

Saturation moments, Curie temperatures, and supporting crystallographic data are reported for a series of ferrimagnetic intermetallic compounds of the stoichiometry R₂Co₁₇, where R is any of the rare‐earth elements Y, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, and Lu. The saturation moment of Y₂Co₁₇ is 27.2, that of Lu₂Co₁₇ is 27.6 Bohr magnetons per formula unit, indicating a cobalt moment of 1.61 _μB in this series. Substitution of Pr and Nd for R raises the saturation to 32.8 _μB/F.U. for Pr₂Co₁₇; all other lanthanides lower it (minimum: 5.7 _μB/F.U. for Ho₂Co₁₇). Except for Sm₂Co₁₇, the values agree well with the concept that the Co moments couple antiparallel with the rare‐earth spin sublattice. For Ce and Pr, a valence>3 and electron transfer from R to Co must be assumed. The Curie temperatures lie between 795° and 940°C. The variation of T_c with the atomic number suggests that two coupling mechanisms are active: direct Co‐Co exchange interaction and indirect exchange between R and Co via polarized conduction electrons.