Cluster glass state and photoinduced effects on the freezing dynamics in KxCo[Fe(CN)6]y.ZH2O (x-0.16,y-0.72, z-4.4)

The magnetic properties and photoinduced magnetization of a Prussian blue analog, KxCo[Fe(Cn)6]y•ZH2O (x-0.16, y-0.72, z-4.4) were systematically studied. The frequency dependence of the linear ac susceptibility, the irreversibility in the field-cooled/ zero-field-cooled magnetization (MFC /MZFC), and the relaxation of MZFC suggest a cluster glass behavior. Illumination with red light leads to an increase in the magnetic irreversibility. While MFC is significantly increased after illumination, MZFC at low temperatures is decreased. The observed photoinduced magnetic effects are explained within a cluster glass model. The photoinduced increase in the concentration of spins leads to a shift of dynamics toward longer length and time scales, resulting in freezing of spin clusters at a higher temperature. © 2000 American Institute of Physics.