Anomalous Transport and Magnetic Properties in Fe2+xV1-xSi in Relation to the Origin of GMR

Abstract

Measurements of electrical resistivity (ρ), magnetoresistance (MR), magnetization (σ) and Mössbauer spectroscopy are performed for Heusler type alloys Fe 2+ x V 1- x Si. At x =0.20 an anomalous peak of residual resistivity and the giant MR (GMR) of -27% in maximum are first observed. The magnetization and Mössbauer measurements show that the moment of a Fe atom in the alloy is determined from the number of other Fe atoms sited at 1st neighbor (local environment model) and the alloy with x =0.20 is ferromagnetic microscopically but not macroscopically. All these results are compared and discussed with the recent theoretical results and other experimental works. The origin of GMR and other anomalies around x =0.20 can be explained qualitatively from the combination of the matrix with low charge carrier concentration and the magnetic cluster determined by the local environment model.