Spin glass behaviour of the spinel system GexCu1−xFe2O4

Ac-susceptibility measurements at various temperatures and hysteresis studies at various fields indicate that the system Ge_xCu_1?xFe₂O₄ (x ? 0.6) contains mixed multidomain, single domain or superparamagnetic states. Sharp susceptibility maxmima, resembling those of spin glasses, are observed for x = 0.1 and 0.2, which may be attributed to the single domain-superparamagnetic (SDSP) transition and the overall behaviour shows a cluster spin glass type of ordering.