Photoinduced Characteristics of Mn Site Doped La0.7Ba0.3Mn0.95X0.05O3 (X=Mn, Cr, Fe, Co) Thin Films

The compounds of La0.7Ba0.3Mn0.95X0.05O3 (X = Mn, Cr, Fe, Co) were prepared by a conventional solid reaction method and then their films were prepared on LaAlO3 single crystal substrate by a magnetron sputtering method. The effects of the Mn site doping of transition elements (Cr, Fe, Co) on the photoinduced properties of the La0.7Ba0.3MnO3 (LBMO) films were investigated. Results indicate that the transition element doping of Cr, Fe or Co causes a decrease of the insulator-metal transition temperature (T-p) and an increase of the maximum relative variation (LRmax) of resistivity and the photoinduced resistivity. Among them, Fe has the largest effect, Co comes second and Cr has the smallest. Laser induction has different influences on the resistivity of films in different temperature zones. In a low temperature zone (T<T-p) the photoinduced resistivity is increased while in a high temperature zone (T>T-p) it is decreased. The intrinsic mechanism of the transport behavior and photoinduced properties was discussed in view of the electronic structure and lattice effect of Cr, Fe and Co.