Rashba-type splitting of the Au(110) surface state: A combined inverse and direct photoemission study

Abstract

The Shockley surface state located at $\overline{\mathrm{Y}}$ on the $(1\ifmmode\times\else\texttimes\fi{}2)$-reconstructed Au(110) surface is predicted to exhibit a Rashba-type spin splitting. Previous photoemission experiments searched for this splitting but it could not be resolved yet. In order to uncover a possible splitting, the unoccupied surface state on Au(110) is examined with spin- and angle-resolved inverse photoemission, whereas Na-covered Au(110) allows for investigation of the now occupied surface state by means of spin- and angle-resolved direct photoemission. Our data show clear spin splittings in the order of $100\phantom{\rule{0.16em}{0ex}}\mathrm{meV}$ with a sign reversal at $\overline{\mathrm{Y}}$ in the surface state's in-plane spin components which is characteristic for a Rashba-type behavior. Furthermore, we deduce an effective mass of ${m}^{*}=(0.27\ifmmode\pm\else\textpm\fi{}0.02){m}_{e}$ and a Rashba parameter of ${\ensuremath{\alpha}}_{R}=(0.46\ifmmode\pm\else\textpm\fi{}0.04)\phantom{\rule{0.16em}{0ex}}\mathrm{eV}\phantom{\rule{0.16em}{0ex}}\AA{}$ from direct photoemission measurements.