Experimental energy-band dispersions and lifetimes for ruthenium

Abstract

We have determined energy-band dispersions and lifetimes for occupied and empty bands along the threefold axis of Ru using angle-resolved photoelectron spectroscopy with synchrotron radiation. The lowest valence band extends from - 7.5 eV below the Fermi energy at ${\Gamma }_1^{+}$ to - 5.6 eV at ${\Gamma }_4^{-}$ with an inverse lifetime of 1.2 eV. There is a band gap between - 5.5 and - 2.8 eV. The $t_{2g}$-like and $e_g$-like $\Gamma$ points are at - 2.4 eV (${\Gamma }_6^{-},{\Gamma }_1^{+}$) and at - 0.3 eV (${\Gamma }_6^{+}$), respectively. A ${\Delta }_5$, ${\Delta }_6$ symmetry gap extends from - 1.7 to - 0.5 eV. A comparison with band calculations is given.