Pseudogap formation in the intermetallic compounds (Fe1-xVx)3Al

Optical conductivity data of the intermetallic compounds (Fe1-xVx)(3)Al (0 less than or equal to x less than or equal to 0.33) reveal that their density of states around the Fermi energy (E-F) is strongly reduced as x is increased. In particular. Fe2VAl (x = 0.33) has a deep, well-developed pseudogap of 0.1-0.2 eV at E-F and a small density (similar to 5 X 10(20) cm(-3)) of carriers, which is highly unusual for intermetallic compounds. It is shown that the pseudogap results from the band structure of Fe2VAl, rather than from temperature-dependent correlation effects. Based on the present results. we propose a simple model that consistently explains both the semiconductorlike transport and the metallic photoemission results previously observed for Fe-2 VAl.