CMR effect and the photo-induced properties in La0.82Te0.18MnO3 thin film

Using pulsed laser deposition method, the La0.82Te0.18MnO3 thin film was prepared on LaAlO3 (012) single crystal substrate. The structure of the film studied by X-ray diffractometry shows that the film has perovskite pseudocubic structure, and is of preferential orientation (012). The R-T curves show the metal-insulator transition (MIT) and CMR effect. And the TMI are 283 K and 303 K for 0 T and 0.7 T, respectively, and they are both near room temperature. The maximum MR is 30.6% at 0.7 T. Correspondingly, the peak temperature at the maximum MR is 263 K. This shows that the films display CMR effect in the mental region. Moreover, the magnetoresistance ratio at the room temperature (303 K) is 4.8% at 0.7 T. The results show that the data satisfy R=P1+P2T2 + P3T4.5 for TMI; when T>TMI, it is satisfied with small polaron model. The effect of the continuous wave laser (532 nm, 40 mW) on the film was also investigated. Below TMI, the resistance increased under photo inducing. Above TMI there was a decrease of the resistance. The maximum photoinduced resistance change is 33.6%. This is attributed to the change of the magnetic order in the film because of photoinducing, which might reduce the double exchange, and change electronic transport.