Transport Properties and Photo-induced Effect in La_(0.9)Ce_(0.1)MnO_3 Thin Film

Using Pulsed Laser Deposition method,the La_(0.9)Ce_(0.1)MnO_3 thin film was epitaxial prepared on LaAlO_3 (100) single crystal substrate.The XRD result shows the film has perovskite pseudocubic structure with preferential orientation (100).The R-T curves show the metal-insulator transition and CMR effect,and the T_(MI) are 213K and 223K for 0T and 0.1T,respectively.The maximum MR is 38.5% at 0.1T.Correspondingly,the peak temperature at the maximum MR is 153K.This indicates that the films display CMR effect in the mental region.The fitting results show that the data satisfy R=R_0+R_1T~2+R_2T~(4.5) for TT_(MI),and for TT_(MI),it is satisfied with small polaron model . The effect of the continue wave laser (532nm,40mW) on the film was also investigated.Below TMI, the resistance increases.Above T_(MI) there is a decrease of the resistance.The TMI shifts to the low temperature when the laser irradiates.This is attributed to the change of the spin order in the film because of photoinducing,reduce the double exchange,and change electronic transport.The resistance meets the exponential formula R(t)=R_0+Aexp(-t/τ),which can interpret the relaxation process from the photoinduced spin correlation state.