Magnetic properties and Mossbauer studies of Y/sub 3-x/Ce/sub x/Fe/sub 5/O/sub 12/ (x=0.00, 0.01, and 0.3) fabricated using a sol-gel method

Compounds of composition of Y/sub 3-x/Ce/sub x/Fe/sub 5/O/sub 12/ (x=0.0, 0.1, and 0.3) were prepared using the sol-gel method. The vibrating samples magnetometer measurements showed no sizable changes in saturation magnetization. A small coercivity (H/sub c/=5.8 Oe), however, was obtained from the Y/sub 2.9/Ce/sub 0.1/Fe/sub 5/O/sub 12/ sample, comparable with that of an undoped Y/sub 3/Fe/sub 5/O/sub 12/ sample (H/sub c/=54.1 Oe). Mossbauer spectra of Y/sub 3-x/Ce/sub x/Fe/sub 5/O/sub 1/2 were measured at various absorber temperatures from 4.2 K to Neel temperature. The temperature dependence of the magnetic hyperfine field in /sup 57/Fe nuclei at the tetrahedral (24d) and octahedral (16a) sites were analyzed based on the Neel theory of ferrimagnetism. For Y/sub 2.9/Ce/sub 0.1/Fe/sub 5/O/sub 12/, the intersublattice a-d superexchange interaction was found to be antiferromagnetic with strength of J/sub a-d/=21.42 k/sub B/, while the intrasublattice interactions a-a, d-d were found to be ferromagnetic with a strength of J/sub a-a/=4.50 k/sub B/ and J/sub d-d/=0.02 k/sub B/, respectively.