A study on Fe-induced structural, magnetic and transport properties in colossal magnetoresistive Nd0.67Sr0.33MnO3 polycrystalline bulk and films

Abstract

The most promising application of the magnetoresistance effect is for magnetoresistive read-back heads used in magnetic storage technology. The magnetic field range in this application is of the order of 0 a?? 20 Oe for the currently used storage density and it is expected to decrease as the storage density increases. This explains why a considerable effort is now focused on the study of manganese oxides that exhibits colossal magnetoresistance (CMR) effect as large as possible at room temperature. Other application of magnetoresistance can be in the field of electric current measurement, position sensors, rotation sensors and microphones. In this dissertation, main attention was paid to the study of magnetic, electrical and magnetotransport in CMR ceramics, thin films and composites. The CMR ceramics were prepared by solid-state reaction technique while the CMR thin films were prepared by pulsed-laser deposition (PLD). The composites were prepared by co-sintering the mixed ceramic powders. The microstructures of the samples were characterized by XRD, AFM, SEM and XPS. The magnetic properties were evaluated using VSM. The electrotransport and magnetotransport properties were measured by a standard four-pad probe method.