On the origin of the magneto-optical effects in Li, Mg, Ni, and Co ferrite

W. F. J. Fontijn, P. J. van der Zaag, R. Metselaar

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Abstract

A reexamination of the magneto-optical (MO) spectra of Li0.5Fe2.5O4, MgFe2O4, NiFe2O4, and CoFe2O4 is presented. Thus far the MO spectra of these compounds have been explained by either orbital promotion processes, oxygen to iron charge transfer transitions or crystal field transitions and, in the case of CoFe2O4, a single intervalence charge transfer (IVCT) transition. For Li0.5Fe2.5O4 and MgFe2O4, the major transitions in the MO–Kerr spectra between 0.5 and 5.0 eV are assigned to intersublattice charge transfer (ISCT) transitions. The MO–Kerr spectrum of NiFe2O4 is more complex as in this case both Fe3+ and Ni2+ contribute to the spectrum. In NiFe2O4 an additional IVCT transition is observed at 2.9 eV. The complex MO spectrum of CoFe2O4 could be resolved using the dielectric tensors of Co2+Al3+𝑥Fe3+2−xO4 (x=0, 0.1, 0.6, and 1) and rigorously fitting both the diagonal and the off-diagonal elements of the dielectric tensor with one set of transitions which was consistent for all degrees of Al3+
substitution. Thus, in these ferrites a consistent assignment of all the major transitions in the 2.0 to 5.0 eV energy range to either IVCT or ISCT transitions is made.
Original languageEnglish
Pages (from-to)6765-6767
Number of pages3
JournalJournal of Applied Physics
Volume83
Issue number11
DOIs
Publication statusPublished - 1998
Externally publishedYes

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