부산대학교 도서관

Temperature dependence of magnetization, anisotropy, and hyperfine interaction parameters of NiFe 2– x Yb x O 4 ( $x = 0$ , 0.05, and 0.075) was investigated, and the results are presented. All the compounds were prepared by solid-state reaction formed in cubic inverse spinel phase with the space group $Fd\overline 3 m$ . Increments in the lattice constant were observed upon partial substitution of Fe 3+ by Yb 3+ . Decreased magnetic moment and increased magnetic anisotropy with Yb 3+ substitution were observed through magnetization measurements, carried out at 5, 100, 200 and 300 K. Analyses of Mössbauer spectra recorded at 5 K and 300 K, revealed decreased hyperfine fields and magnetic moments at the B-site (and hence net moment) with increasing Yb 3+ content. In addition all the compounds exhibited Neel-type, collinear ferrimagnetic structure.