Origin of the magneto-optical properties of iron garnets

• Published in: Physica. B, Condensed matter Condensed matter, 1991-03, Vol.168 (3), p.187-196
• Main Authors: Moskvin, A.S., Zenkov, A.V., Yuryeva, E.I., Gubanov, V.A.
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Magnetooptical effects; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of bulk materials and thin films; Physics
• ISSN: 0921-4526; 1873-2135
• DOI: 10.1016/0921-4526(91)90670-A

The analysis of experimental optical and magneto-optical spectra of iron garnets R3Fe5O12 shows that all peculiarities of these spectra in a wide range, 2–6 eV, can be explained by means of oxygen-to-iron charge-transfer (CT) transitions in octahedral FeO9-6 complexes and tetrahedral FeO5-4 complexes, being the main magneto-optical centres in iron garnets. The values of effective orbital Landé factors and spin-orbit coupling constants for CT states in octahedral and tetrahedral complexes are obtained. From the standpoint of the decisive role of CT transitions, using theoretical values of the above-mentioned parameters, a microscopic model calculation is carried out of the contributions to the Faraday rotation of yttrium iron garnet, which are proportional to the magnetizations of a- and d-iron sublattices and to the external magnetic field. Results of the model calculation are in good agreement with experimental data.