GMR in Heusler type alloys Fe2+xV1-xAl

Electrical resistivity (rho), magnetoresistance (MR) and magnetization (sigma) for Heusler type alloys Fe2+xV1-xAl with -0.10 less than or equal to x less than or equal to 0.20 were measured. A giant magnetoresistance (GMR) of about 40% was observed for the weakly inhomogeneous ferromagnet Fe2.1V0.9Al at 4.2 K in 139 kOe. In the ferromagnetic alloys (x greater than or equal to 0.10) the rho showed a maximum near the Curie temperature (T-C) and the temperature coefficient of resistivity (TCR) was negative above T-C. For the paramagnetic alloys (x less than or equal to 0.05) TCR was negative in the entire temperature (T) range examined. Tn the low T range, the alloys with x less than or equal to 0.10 exhibited variable-range hopping (VRH) conduction behavior, ln rho proportional to T-1/4. The magnetism of the present alloys was explained on the basis of the concept of magnetic clusters. The origin of the present GMR was discussed in relation to the Anderson localization of carriers in alloys having atomic and magnetic disorders.