Magnetooptical activity of the Tb3+ non-Kramers ion in Y3Al5O12

Features of the temperature dependence of magnetic circular dichroism (MCD) in Y3Al5O12 on the allowed 4f --> 5d transition with a center at lambda = 271 nm are shown to be determined by the type of Stark splitting of the gro und F-7(6) multiplet of the Tb3+ ion in the garnet structure. The major con tribution to MCD of the Tb3+ ion in Y3Al5O12 at T less than or similar to 3 00 K is found to be made by transitions from the quasi-doublets Gamma(1), G amma(4) and Gamma(3), Gamma(2) Of the F-7(6) multiplet to the Gamma(2), Gam ma(4) sublevels of the mixed excited 4f(7)5d configuration of the Tb3+ ion.