Determination of magnetic anisotropy of complex rare-earth compounds from Mössbauer and NMR spectra

Abstract

Experimental data and theoretical papers on the magnetic anisotropy (MA) of rare-earth-transition metal intermetallic compounds are reviewed. Discrepancies between the experimental data obtained by different authors, as well as between these data and the theoretical calculations of the MA constants, are indicated. A technique is proposed for determining the crystal-field parameters and the effective charges Q ^*_i of ions in intermetallic compounds. Using experimental Mössbauer and NMR spectroscopic data, possible values of Q ^*_i are determined for R ₂T_17−x and R ₂T_17−x Ti_x compounds, which allow one to find the MA constants of these systems with different R and T in a unified way. The problem of the sign of the contribution from the rare-earth metal sublattice to the MA is discussed. The heavy x dependence of this contribution in the R ₂T_17−x Ti_x system is explained to be due to the contribution to the crystal field from Ti ions in the dumbbells.