Influence of MOCVD technological conditions on magnetoresistance of nanostructured La-Ca-Mn-O films used for magnetic field sensors

Abstract

The results of structure and magnetoresistance (MR) of nanostructured La0.78Ca0.22MnO3 films, grown at different gas pressure (from 3 to 7 Torr) by metal–organic chemical vapor deposition (MOCVD) technique, are presented. The MR was investigated in pulsed magnetic fields up to 60 T in the temperature range 1.5–294 K. The results were analyzed from the perspective of using these films for magnetic field sensors operated at low temperature. It was demonstrated that with the increase of the Ar+O2 gasses pressure, the surface morphology of the films becomes rougher and grain size increases. Meanwhile at low temperature the magnetoresistance of the films grown at low pressure has a higher value. It was demonstrated that in the range of lower magnetic fields (up to 10 T) the films grown at low gas pressure have higher sensitivity. However, for measurement of higher magnetic fields, the properties of films grown at higher gas pressure are favored. The obtained results allow evaluating the influence of MOCVD technological conditions on magnetoresistance of La-Ca-Mn-O manganites used for pulsed magnetic field sensors.