| Magneto-electronics lies in the area of current scientific interest in condensed matter physics and materials sciences, due to abundant physics conceptions and applied potentials. It is the base of magnetic devices with high density and sensitivity. Recently, magnetic computer memory is expected to have a large economic impact, and has been significantly focused on its experimental research. In order to demands of practical application, it needs to be of a large magnetoresistance effect at room temperature and at low magnetic filed. At the same time, with the development of materials science, many researchers pay much attention to study on composites, which exhibit not only single component but also some astonishing properties in composites. Therefore, it is of importance to study magnetic properties of composites with the variation of microstructure. The thesis was originally intended to study the Sr2FeMoO6/glass composites; work is mostly focused on the magnetotransport properties with different electrical and spin polarization. Through the modulation of grainboundary by glass insulator, it effectively reduced the coupling field and strengthened the tunnel among granular. As a result, we successfully obtained an enhanced low field magnetoresistance.Here the pure polycrystalline Sr2FeMoO6 bulks were synthesized by conventional solid-state reaction, and then they were mixed with appropriate mass proportion of glass. For such Sr2FeMoO6/glass composites, their structure,magnetization and magnetotransport properties were studied subsequently. From X-ray diffraction (XRD) data, it was found that the crystal structure of polycrystalline Sr2FeMoO6 is not changed, with the glass phase lying in the grianboundaries probably. The measurements of resistivity at zero field and...
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