Increase of operating temperature of magnetic field sensors based on La–Sr–Mn–O films with Mn excess

Abstract

The magnetoresistance of nanostructured La-Sr- Mn-O films with Mn excess was investigated in the temperature range of (100-343) K in pulsed magnetic fields up to 20 T. The films having different Mn excess (5%, 10% and 15%) were grown using the Pulsed-injection metal-organic chemical vapor deposition technique onto a polycrystalline Al2O3 substrate. It was obtained that increase of Mn excess leads to the shift of the metal-insulator transition temperature Tm to higher temperatures and to decrease of the resistivity maximum m. As a result, the highest magnetoresistance values at temperatures higher than 320 K were obtained for the films with Mn excess of 15%. It was demonstrated that the increase of Mn content in La- Sr-Mn-O films allows to use them for the development of high pulsed magnetic field sensors operating at temperatures up to 70oC.