Multiplet splitting of mixed spinelsNiFexCr2−xO4and its relation to magnetic hyperfine fields

The x-ray photoelectron spectra of Ni $3s$ and Cr $3s$ for the mixed spinels $\mathrm{Ni}{\mathrm{Fe}}_x{\mathrm{Cr}}_{2-x}{\mathrm{O}}_4 \left(0\mathrm{}\le x\le 2\right)$ were measured at room temperature. The multiplet splitting of Ni $3s$ was compared with an average magnetic hyperfine field determined by Mössbauer spectroscopy. It is found that the multiplet splitting is nearly constant as a function of chemical composition. This suggests that the large values found for the hyperfine field on tetrahedral sites may be due to orbital contributions.