Pseudogap Formation in the Intermetallic Compounds $({\mathrm{Fe}}_{1-\mathit{x}}{V}_{\mathit{x}}{)}_3\mathrm{Al}$

Optical conductivity data of the intermetallic compounds $({\mathrm{Fe}}_{1-x}{\mathrm{V}}_x{)}_3\mathrm{Al}$ ( $0\le x\le 0.33$) reveal that their density of states around the Fermi energy ( $E_F$) is strongly reduced as $x$ is increased. In particular, ${\mathrm{Fe}}_2\mathrm{VAl}$ ( $x=0.33\mathrm{}$) has a deep, well-developed pseudogap of $0.1–0.2\mathrm{eV}$ at $E_F$ and a small density ( $\sim 5\times {10}^{20}{\mathrm{cm}}^{-3\mathrm{}}$) of carriers, which is highly unusual for intermetallic compounds. It is shown that the pseudogap results from the band structure of ${\mathrm{Fe}}_2\mathrm{VAl}$, 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 ${\mathrm{Fe}}_2\mathrm{VAl}$.