Polar Kerr Effect of Magnetite in the Visible and Near Infrared Spectral Regions

Abstract

a) Polar Kerr rotation and ellipticity of the synthetic single crystal magnetite are measured a t room temperature in the 400 to 2400 nm spectral region. Using these magnetooptical measurements together with the earlier optical data the diagonal and the off-diagonal tensor elements of the dielectric function are deduced. In the infrared region the dependences are dominated by the presence of the charge carriers while the behaviour in the visible part of the spectra is mainly due to the 3d crystal field transitions of the tetrahedral and octahedral iron ions.La rotation e t I'ellipticit6 Ken-polaire d'un monoeristal de magn6tite synthbtique ont 6t6 mesur6es dans la bande spectrale de 400 B 2400 nm la temperature ambiante. En utilisant ces mesures magn6tooptiques combinks avec les resultats optiques recents on a d6duit les Blements diagonaux e t non-diagonaux du tenseur diblectrique. Dans la bande infrarouge les spectres sont domines par la presence des porteurs de charge 6lectrique tandis que le comportement dans la partie visible du spectre est du principalement aux transitions des electrons entre des niveaux 3d des ions de fer occupant des sites t6tra6driques e t octakdriques.

Optical and magneto-optical polar Kerr spectra ofFe3O4andFontijn1, Zaag2, Devillers3 et al. 1997Phys. Rev. B179161080View full textAdd to dashboardCite

“…12͒ in accordance with the proposition of Feil. 7 Assignment of the band at 1.94 eV is more complex because several transitions, including weak crystal-field transitions, 10,11 overlap here. The main transition, however, is IVCT: t 2g →e g between ͓Fe 2ϩ ͔ and ͓Fe 3ϩ ͔.…”

“…7͒ of pure Fe 3 O 4 are in fair agreement with those reported in the literature. 10,12,36 The best way to study magneto-optical transitions is to examine the off-diagonal element of the dielectric tensor, where diamagnetic and paramagnetic transitions can be identified at their exact frequency and linked to their microscopic origin. Therefore, we will focus on the dielectric tensor in the remainder of this paper.…”

“…Š imša and co-workers reported the polar Kerr rotation and ellipticity of Fe 3 O 4 as well as the influence of a systematic substitution of Fe 2ϩ by Mn 2ϩ in the 0.5-3.0 eV energy range. 10,11 In their study the peak at 0.9 eV in the Kerr rotation spectrum of Fe 3 O 4 was ascribed to the presence of charge carriers ͑i.e., Fe 2ϩ ͒ and was assumed to be related to charge transfer between ͓Fe 2ϩ ͔ and ͓Fe 3ϩ ͔. The spectrum around 2.0 eV was explained in terms of 3d crystal-field transitions of iron ions on tetrahedral sites.…”