ANOMALOUS GIANT MAGNETORESISTANCE IN HEUSLER-TYPE ALLOYS FE2-XGA(XV1)

Electrical resistance, magnetoresistance and magnetization were measur ed for Heusler-type alloys, Fe2+xV1-xGa. An anomalous giant magnetores istance (GMR) near 50% was observed for Fe2VGa which was a weak and in homogeneous ferromagnet. For alloys with x > 0, which show clear ferro magnetism, the electrical resistance showed an anomaly below the Curie temperature. For alloys with x < 0, the temperature dependence of the resistance indicated behavior like that of a semiconductor. The energ y gap was tentatively estimated to be 0.03 eV for x = -0.10. The origi n of the present GMR is discussed in terms of the metal-insulator tran sition arising from ordering of the magnetic moment.