Enhanced non-metallic behavior on the verge of magnetic instability in Fe2V1−xNbxAl Heusler alloys

Abstract Structural, magnetic and transport behavior of Nb substituted Fe 2 VAl alloys have been investigated in the present work. From the detailed analysis of these data it is observed that Nb content promotes a lattice expansion in L2 1 super-structure of Fe 2 VAl. Magnetization data suggest that un-doped Fe 2 VAl exhibits cluster glass behavior with a bimodal distribution of superparamagnetic clusters at lower temperatures, developed possibly due to the cluster size distribution. However, in Nb-substituted alloys, cluster size reduces and cluster density increases, which further reduces coupling between the clusters, resulting in a state of increased magnetic disorder up to a plausible 20% substitution. Concurrently resistivity increases at lower temperatures and shows a deviation from semiconductor like transport, which can be explained in terms of increasing spin dependent scattering and decreasing inter cluster interaction due to iso-electronic-but-larger-sized Nb substitution at V site. Present experimental results corroborate well with the theoretical predictions made in the literature.