Angular variation of magnetic linear dichroism in Ru-doped YIG(+)

Ru distribution in Y3Fe3O12(YIG) is investigated by studying the symmetry of the magnetooptical properties above 1μm wavelength. The method utilized is the recently proposed angular variation of induced anisotropy (AVIA) and Consists in measuring, as the crystal is rotated, the angular variation of an induced anisotropy-property, thus obtaining a pattern from which the site symmetry may be derived. Linear dichroism induced by a saturating magnetic field, MLD, is the anisotropy property utilized to determine the symmetry of the ruthenium centers. The near-infrared absorption spectrum exhibits two distinct regions, one at about λ = 1.3μm and the other one at about λ =2.0μn. The AVIA experiment at the higher-energy region shows a marked octahedral character. The behavior under reducing treatment in H2atmosphere allows identification with Ru⁴⁺so that this absorption is associated with a Ti→⁵E, E transition of octahedral Ru⁴⁺. Furthermore the exitence of a symmetry-lowering distortion of the octahedral center is determined. The Seebeck coefficient is measured and the conduction is found to be n-type. The possibility is discussed that charge compensation of Ru⁴⁺is provided by Fe²⁺to be associated with the 2μm absorption region.