A Mössbauer Spectroscopy and Nuclear Magnetic Resonance Study of R₂(Fe,Co)₁₄B and Related Compounds

Abstract

From the Mössbauer and NMR spectroscopy study of the hyperfine interaction parameters in R₂(Fe,Co)₁₄B and RFe_12-xM_x the local magnetic momentsat the 6 different Fe crystallographic sites in the former and at the 3 types of sites in the latter ones were derived and found in good agreement with the moments of the unit cells measured magnetically.

In the case of RFe_12xM_x the statistcal. distribution of M on one or more types of Fe sites gives rise to a splitting and broadening of the Mossbauer lines which makes necessary a substantial increase of the number of fitting lorentzian sextets. The position and the width of the B NMR signals in R₂Fe₁₄B and R₂Co₁₄B are mainly determined by the transferred hyperfine fields from the Fe or Co neighbours and in a large extent by the distribution of the dipolar fields in the domain walls of the compounds with uniaxial or planar anisotropy.