Cluster-glass state and photon-induced effects in perovskite manganite (La0.3Nd0.7)(2_3)Ca1_3MnO3 films

The electrical and magnetic properties and photon-induced effects in perovskite manganite thin films of (La 0 . 3 Nd 0 . 7 ) 2 / 3 Ca 1 / 3 MnO 3 with the tolerance factor t0.908 are investigated. The persistent photoconductivity (PPC) effect induced by a He-Ne laser with a photon energy of ∼2 eV and the normal photoconductivity (NPC) effect induced by a mercury lamp with photon energy near 3 eV are observed at low temperatures where the system is in (or close to) the cluster-glass (CG) state. The observed resistivity relaxations induced by laser illumination and magnetic field indicate that the CG state is unstable. The PPC, NPC, and magnetic effects are originated from different mechanisms and can be understood based on the particular CG-state-related phase separations.