The behavior of photoinduced charge delocalization in bilayer manganite LaCa2Mn2O7

The properties of electrical and magnetic transport in bilayer perovskite manganite LaCa2Mn2O7, were investigated by the measurements of resistivity and magnetization. A distinct increasing in resistivity at low temperatures, which is in good agreement with an obvious decreasing in magnetization at the corresponding temperature region was observed. It was suggested that the sample undergoes a transition from ferromagnetic metallic to charge localization state caused by the antiferromagnetic charge ordering (CO). The behavior of photoinduced charge delocalization was observed under irradiation of He–Ne laser (632.8 nm) at the low temperatures. It can be explained in terms of the effect of photoinduced charge transfer from O-2p to Mn4+-3d eg orbital state resulting in the partial melting of CO state.