Cluster glass state and photoinduced effects on the freezing dynamics in KxCo[Fe(Cn)(6)](y)center dot ZH(2)O (x similar to 0.16, y similar to 0.72, zsimilar to 4.4)

The magnetic properties and photoinduced magnetization of a Prussian blue a nalog, 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 th e linear ac susceptibility, the irreversibility in the field-cooled/zero-fi eld-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 afte r illumination, M-ZFC at low temperatures is decreased. The observed photoi nduced magnetic effects are explained within a cluster glass model. The pho toinduced increase in the concentration of spins leads to a shift of dynami cs toward longer length and time scales, resulting in freezing of spin clus ters at a higher temperature. (C) 2000 American Institute of Physics. [S002 1-8979(00)18108-3].