Mössbauer studies of ZnCr2xGa2−2x O4 spinel solid solutions: A cluster spin glass for 0.6 ≲x ≲ 0.85

Abstract

Mossbauer studies of topologically frustrated ZnCr2xGa2−2xO4 system (0.6 ⩽ x ⩽ 1) are performed. Almost all the spectra consist of a superposition of a paramagnetic doublet and an enlarged magnetic hyperfine pattern. Two models are used to fit the spectra, a static hyperfine field distribution method and a superparamagnetic type relaxation simulation method. In the composition range 0.6 ⩽ x ⩽ 0.85, for which spin glass behavlour has been evidenced, only the second model gives coherent results rather in agreement to a dynamic non equilibrium process with a progressive freezing of cluster moment.