INFLUENCE OF THE SUPEREXCHANGE INTERACTIONS ON THE SATURATION MAGNETIZATION AND CURIE-TEMPERATURE IN SUBSTITUTED YTTRIUM IRON GARNETS

The influence of the substitution with nonmagnetic ions on the magneti c moment M and the Curie temperature T-C has been investigated in Y3-2 xCa2xVxInyAlzFe5-x-y-zO12 (0 less than or equal to x less than or equa l to 1; 0 less than or equal to y less than or equal to 1; 0 less than or equal to z less than or equal to 2). The statistics of superexchan ge interactions developed by Gilleo has been applied. An additional de crease of the superexchange interactions caused by the magnetic ions e xcluded from ferrimagnetism has been taken into account. The results o btained show that the correction improves the accuracy in the predicti on of the magnetic moment and the Curie temperature. The higher T-C in V-substituted garnets has been explained with the indirect influence of the nonmagnetic V ion which increases the strength of the superexch ange interactions.