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

• Published in: Journal of magnetism and magnetic materials Vol. 324; no. 6; pp. 1071 - 1079
• Main Authors: Saha, Ritwik, Srinivas, V., Chandrasekhar Rao, T.V., Banerjee, A.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.03.2012; Elsevier
• Subjects: Cluster glass; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Conductivity phenomena in semiconductors and insulators; Diamagnetism, paramagnetism and superparamagnetism; Domain effects, magnetization curves, and hysteresis; Electronic transport in condensed matter; Exact sciences and technology; Galvanomagnetic and other magnetotransport effects; Heusler alloy; Magnetic properties and materials; Magnetization; Magnetization curves, magnetization reversal, hysteresis, barkhausen and related effects; Magnetoresistance; Physics; Pseudo-gap; Pseudo-gap; Magnetization; Magnetoresistance; Heusler alloy; Cluster glass; Vanadium alloys; Niobium alloys; Iron alloys; Superparamagnetism; Aluminium alloys; Temperature effects; Particle interactions; Heusler alloys; Chemical composition; Carrier density; Transition element alloys
• ISSN: 0304-8853
• DOI: 10.1016/j.jmmm.2011.10.025

Structural, magnetic and transport behavior of Nb substituted Fe2VAl 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 L21 super-structure of Fe2VAl. Magnetization data suggest that un-doped Fe2VAl 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. ► Present study on Fe2V1−xNbxAl show that lattice expansion takes place on increasing Nb. ► Experimental results are consistent with predicted trends from band structure calculation. ► It is shown that the lattice expansion plays a role in observed unusual physical properties. ► Analysis of magnetic data confirms the presence of magnetic clusters (site disorder). ► Finally we show that the magnetic and electrical properties are interrelated.