Magnetic properties of (Zn,Cd,Cu)–Co–Fe–Ti spinel oxides

AC susceptibility, magnetization and Mössbauer spectra have been measured for (Zn,Cd,Cu)0.5Co0.9Fe1.2Ti0.4O4 and Zn0.3Co0.9Fe1.4Ti0.4O4 spinel oxides. The variation of coercive field below the spin glass transition temperature Tsg is found to fit a double exponential function of the form \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document} $$H_c \left( T \right) = H_{1e} ^{ - \beta _1 T} + H_{2e} ^{ - \beta _2 T} $$ \end{document}, where Hi and βi are constants. Mössbauer spectra and analysis show superparamagnetic fluctuations associated with magnetic clusters. Symmetric doublets above Tsg are decomposed into quadrupole doublets associated with tetrahedral (A) and octahedral (B) sites.