CONTRIBUTION OF THE TERBIUM ION TO THE FARADAY-ROTATION OF TERBIUM-YTTRIUM FERRITE GARNETS

Faraday Rotation (FR) measurements performed on single crystal terbium-yttrium iron garnets (Tb0.35Y2.35Fe5O12) are reported at 1.15 μm wavelength in the temperature range 6-300 K, under magnetic field up to 20 kOe applied along the [111] and [100] directions. The spontaneous FR is isotropic while the 'FR susceptibilities are anisotropic at low temperature, anisotropy which originates mainly from spin reorientation transitions. To analyse the terbium contribution to FR, the Fe3+ contribution is identified to the YIG data: the electric dipole contribution of the Tb3+ ion is found well described by the 'one-ion' model. © 1990.