Temperature dependence of magnetoresistance effect in Ag-Fe3O4 composites films

Abstract We have observed an anomalous magnetoreisistance effect in Ag x -(Fe 3 O 4 ) 1− x composite films. A positive MR value is found at small values of x . As the temperature is decreased, the positive MR ratio becomes significantly larger and appears with a wider range of x . The thermal influence on magneto-transport behavior in Ag x -(Fe 3 O 4 ) 1− x composite films confirms that the spin injection from Fe 3 O 4 into Ag granules induces spin accumulation in Ag granules and thus impede the current causing a larger resistance under a field.