Research On Transport And Phase Transition In (La_1-xPr_x)_2/3Sr_1/3 MnO₃ Thin Films

Thin films of (La_1-xPr_x)2/3Sr1/3MnO3 (x= 1, 1/3, 2/3, 1) have been deposited using the direct current magnetron sputtering method from the targets prepared by the solid state reaction technology. The XRD analysis shows the targets have the structure wih psedudocube perovskite and the films indicate the epitaxial character.The temperature dependences on the resistance in all the thin films show that in the low temperature range the width of eg band level changes the transports, but in the high temperature range the thin films forms the small polarons hopping conductivity. The phase transition induced by the current is explained by the demagnetization and lattice distortion. The photo-induced phase transition of the different light intensities, photo-energies and directions of the polarized light is investigated. It suggested that the photo excites the down spin eg electrons and destroys the spin order system of the thin films. The relation between the He-Ne laser reflectivity of the thin film, applied current and resistance was analyzed by the optics theory of solid state physics.