We have measured the Hall resistivity for the intermetallic compound ${\mathrm{Fe}}_{3-x}{\mathrm{V}}_x{\mathrm{Al}}_y$ $(x=0.5\mathrm{}–1.05;$ $y=0.95,1.05)$ at room temperature. The Hall coefficient changed its sign from positive to negative around the Heusler composition (i.e., $x=y=1)$ with increasing x value or decreasing y value. We have measured the temperature dependence of the Hall coefficient and the electrical resistivity for ${\mathrm{Fe}}_{1.98}{\mathrm{V}}_{1.02}\mathrm{Al}$ and quenched ${\mathrm{Fe}}_{1.95}{\mathrm{V}}_{1.05}\mathrm{Al}$ in the temperature range of 5–300 K. These two compounds showed very different behavior in the electrical resistivity but the behavior of the Hall coefficient was quite similar. At higher temperatures, the Hall coefficient showed a strong temperature dependence but it approached a constant value at low temperatures suggesting that these compounds are semimetals with a pseudogap. The charge carrier density was found to be less than a few tenths per unit cell. The rise of electrical resistivity at low temperatures is not owing to an energy gap but due to magnetic scattering while the negative temperature coefficient at high temperatures is attributable to pseudogap.

• Received 1 February 2001

DOI:https://doi.org/10.1103/PhysRevB.65.075204