FARADAY-ROTATION OF TERBIUM - YTTRIUM FERRITE GARNET

Faraday Rotation (FR) measurements performed on single crystals Terbium-Yttrium Iron Garnets are reported at 1.15 micron wavelength for three terbium contents (1.98 1.02 and 0.35) in the temperature range 6–300 K, under magnetic field up to 20 kOe applied along [111] and [100] directions. The spontaneous FR (associated with the spontaneous magnetization) are isotropic while the “FR susceptibilities” are anisotropic at low temperature, anisotropy which originates mainly from spin reorientation transitions. To analyze the terbium contribution to FR the Fe contribution is identified to the YIG data. The terbium electric dipole transitions coefficient is found to present a linear temperature dependence in the temperature range 100 - 300 K as previously observed in the pure TbIG. © 1990 IEEE