${\mathrm{Cu}}_{0.5}$${\mathrm{Fe}}_{0.05}$${\mathrm{Cr}}_2$${\mathrm{S}}_4$ has been studied by Mössbauer spectroscopy and x-ray diffraction. The crystal structure is found to be a cubic spinel with the lattice parameter $a_0$=9.922 Å. The temperature dependence of both the magnetic hyperfine field and magnetization is explained by the Néel theory of ferrimagnetism using three exchange integrals: $J_{\mathrm{Fe}\mathrm{-}\mathrm{Cr}/k_B=\mathrm{-}}$13.7 K, $J_{\mathrm{Fe}\mathrm{-}\mathrm{Fe}/k_B=\mathrm{-}}$8.3 K, and $J_{\mathrm{Cr}\mathrm{-}\mathrm{Cr}/k_B}$=8.7 K.

• Received 15 May 1989

DOI:https://doi.org/10.1103/PhysRevB.41.62