Modulation of Insulator-Metal Transition Temperature by Visible Light in La_7/8Sr_1/8MnO₃ Thin Film

Effects of magnetic field and light illumination on the electrical transport properties of La_7/8Sr_1/8MnO₃ thin film grown on a Si substrate are investigated. The film shows an insulator-metal transition at T_P≈191.9 K and a low-temperature resistance minimum at T_min≈48 K in darkness. Both magnetic field and light illumination shift the insulator-metal transition temperature T_P to be higher, while the low-temperature transport properties of the film induced by them show different trends. That is, the magnetic field and light illumination make the T_min shift to lower and higher temperatures, respectively. The enhancement of both T_P and T_min under light illumination could be explained in terms of photoinduced hole-doping and demagnetization effects of La_7/8Sr_1/8MnO₃.