Crystal Field Splitting in Octahedral and Tetrahedral Symmetry for Fe3+ Ions in Y3Fe5012

Abstract The crystal field splitting of the energy levels of Fe 3+ ions in octahedral and tetrahedral sites of Y 3 Fe 5 O 12 have been computed between 10000 and 32000 cm −1 . The calculation is performed using, first, the cubic field approximation, then the effect of a trigonal distortion, and finally the spin‐orbit interaction in the two magnetic sites. It is shown that the contributionof thetrigonal distortion to the absorption spectrum can be neglected. Thespin‐orbit coupling does not disturb the value of the calculated level energies but induces a coupling between some multiplets. With the use of the spin‐orbit coupling a very good fit between the computed and theexperimental spectra is obtained leading to an assignment of the observed absorption lines which is slightly different from that obtained without the spin‐orbit coupling effects.