Investigation of Magnetoresistance and Its Anisotropy of Thin Polycrystalline $La_{0.83}Sr_{0.17}MnO_3$ Films in High Pulsed Magnetic Fields

The results on the study of grain boundary effects and influence of film deposition conditions on the magnetoresistance and its anisotropy in polycrystalline $La_{0.83}Sr_{0.17}MnO_3$ films are presented. The magnetoresistance was measured in high pulsed magnetic fields up to 25 T (pulse duration ≈ 0.6 ms) in the temperature range of 120-300 K. A modified Mott hopping model was applied to describe the main behavior of high-field magnetoresistance for both ferromagnetic and paramagnetic phases of the polycrystalline films by taking into account the demagnetization field of the films measured in low magnetic fields perpendicular to film plane. It was also found that to obtain the higher magnetoresistance saturation field at room temperature it is necessary to use the films with smaller crystallites (D ≈ 100 nm). Such films could be used for design of megagauss pulsed magnetic field sensors.