Multi-field modulation of transport properties in critical state (La_1-yPr_y)_0.5Sr_0.5MnO₃ thin films

In this letter, we report the related transport properties of (La_1-yPr_y)_0.5Sr_0.5MnO₃ (y = 0.1, 0.2, 0.3, 0.4 and 0.5) films prepared by pulsed laser deposition. The transport properties of the films with different fields applied, such as optical field, magnetic field and strain field, were investigated. The results show that the resistance increases and the metal–insulator transition temperature shifts to lower temperature with the increasing of Pr doping. However, the film with the doping amount of 0.5 exhibits an insulation characteristic, and showed transient photoconductivity effect, with a relative change of photo-resistance of 7.2% at low temperature. Otherwise, a negative magneto-resistance of 54% was observed at 80 K and 1 T magnetic field. Further, by using an external electric field to modulate the films grown on the PbMg_1/3Nb_2/3O₃-PbTiO₃ substrate, it was found that the electric field reduced the resistance and had a faking effect on the relative change of the photo-resistance. It is mainly attributed to the influence of the external field on lattice distortion and charge carrier delocalization.