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). ZH(2)O (x similar to 0.16, y similar to 0.72, z similar to 4.4) were systematically studied. The frequency dependence of the linear ac susceptibility, the irreversibility in the field-cooled/zero-field-cooled magnetization (M-FC/M-ZFC), and the relaxation of M-ZFC suggest a cluster glass behavior. Illumination with red light leads to an increase in the magnetic irreversibility. While M-FC is significantly increased after illumination, M-ZFC 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. (C) 2000 American Institute of Physics. [S0021-8979(00)18108-3].