Weak itinerant ferromagnetism in Heusler-type Fe2VAl0.95

We report measurements of the magnetic, transport, and thermal properties of the Heusler-type compound Fe2VAl0.95. We show that while stoichiometric Fe2VAl is a nonmagnetic semimetal a 5% substitution on the Al site with the 3d elements Fe and V atoms leads to a ferromagnetic ground state with a Curie temperature TC=33±3 K and a small ordered moment μs=0.12μB/Fe in Fe2VAl0.95. The reduced value of the ratio μs/μp=0.08, where μp=1.4μB/Fe is the effective Curie-Weiss moment, together with the analysis of the magnetization data M(H,T), show magnetism is of itinerant nature. The specific heat shows an unusual temperature variation at low temperatures with an enhanced Sommerfeld coefficient, γ=12 mJ K−2 mol−1. The resistivity, ρ(T), is metallic and follows a power law behavior ρ=ρ0+ATn with n≈1.5 below TC. With applying pressure, TC decreases with the rate of (1/TC)(dTC/dP)=−0.061 GPa−1. We conclude substitution on the Al site with Fe and V atoms results in itinerant ferromagnetism with a low carrier density.