Spin-glass ordering in a spinel ferrite, Mg(Al, Fe)2O4

Non-linear susceptibility (chi (nl)) measurements on MgAl1.4Fe0.6O4 show spin-glass ordering in a cubic spinel ferrite, for the first time. The ordering gives a peak in the temperature dependence of chi (nl), which shows that the spin ordering is a cooperative phase transition. The values of the critical exponents, obtained from chi (nl) as the temperature approaches the transition temperature, are found to lie in the range obtained from measurements on other spin glasses. We also investigate the static and dynamical effects of the spin-glass ordering on Mossbauer spectra. Dynamical spin freezing as a result of spin-glass ordering is observable in Mossbauer spectra.