Electrical resistivity anomaly and magnetic properties in Heusler-type Fe2VAl alloy

Abstract

We have measured the temperature dependence of electrical resistivity, specific heat and magnetization of (Fe1-xVx)3Al alloys with V compositions 0.33≤x≤0.36. The near-stoichiometric Fe2VAl (x = 0.33) exhibits a semiconductor-like behaviour with the resistivity reaching 30 μΩm at 4.2 K. When the V composition deviates slightly from stoichiometry, the low-temperature resistivity is reduced to only 3 μΩm for x = 0.34, showing a positive slope in its temperature dependence below 300 K, but turns to increase remarkably for x>0.34. Plots of the specific heat over temperature, C/T, versus T2 for x=0.33 show an anomalous upturn with decreasing temperature, and the magnetization data provide an evidence of local moment magnetism. In contrast, the enhancement of the specific heat and magnetization is considerably suppressed for x=0.34, being consistent with recent band calculations which predict that Fe2VAl is a nonmagnetic semimetal. The semiconductor-like resistivity behaviour is most likely caused by strong spin fluctuations of Fe impurities on the nominally V site in Fe2VAl.