Electronic structure, magnetic properties and electrical resistivity of the Fe₂V_1−<i>x</i>Ti_<i>x</i>Al Heusler alloys: experiment and calculation

Abstract

The aim of this work is to investigate electronic structure, magnetic properties and electrical resistivity of Fe(2)V(1-x)Ti(x)Al Heusler alloys. Numerical calculations give a pseudogap at the Fermi level for the majority-spin band of Fe(2)TiAl and a magnetic moment larger than 0.9 μ(B), whereas the ground state of Fe(2)VAl is calculated as a nonmagnetic semimetal with a very low total density of states at the Fermi level. In our calculations the remaining alloys of the Fe(2)V(1-x)Ti(x)Al series are nonmagnetic for x<0.1 and weakly magnetic for 0.1<x≤1. The magnetic moment μ of the series of Fe(2)V(1-x)Ti(x)Al compounds scales with the number of valence electrons and fits well to the Slater-Pauling curve. We also present a study of the electronic transport properties and magnetic susceptibility. The resistivities ρ(T) of Fe(2)VAl and Fe(2)V(0.9)Ti(0.1)Al are large and exhibit a negative temperature coefficient dρ/dT of the resistivity between 2 and 300 K. Below 20 K, ρ(T) also shows an activated character. The magnetic susceptibility of Fe(2)VAl and Fe(2)V(0.9)Ti(0.1)Al shows a maximum at ∼2 K which could reflect either the disorder effect or the hybridization gap, characteristic of Kondo insulators.