Photoinduced characteristics in La0.67Ca0.33MnO3 film

A systematic investigation of photoinduced properties is carried out in La0.67Ca0.33MnO3 film prepared on LaAlO3 (100) substrate by magnetron sputtering method. At T < 270 K, the resistivity of film induced by laser increases because of the demagnetization effect of manganites. The photoinduced relaxation character of film indicates that the time constant increases with increasing temperature, which is attributed to the growing thermal fluctuation. After laser irradiation, the resistivity returns to the original value and the relaxation time seems to be independent of temperature. In insulating state, laser irradiation induces the reduction in resistivity of film due to the excitation of small polarons.