Complex manifold of Rashba and image-potential states on Bi/Ag(111)

Abstract

Angle-resolved, mono- and bichromatic two-photon photoemission was used to study the electronic structure at the surface of the giant Rashba system Bi/Ag(111). The photoemission intensity maps are exceptionally rich in structure due to a large manifold of initial and intermediate states that allow for various resonant interband transitions. Using different photon energies, we succeeded in disentangling the complex experimental data. Close to the Fermi level the unoccupied, Rashba-split ${p}_{x}{p}_{y} ({m}_{j}=1/2)$ surface state can be identified with a Rashba parameter of $3.0\ifmmode\pm\else\textpm\fi{}0.2$ eV \AA{} and a lifetime of $26\ifmmode\pm\else\textpm\fi{}5$ fs. At higher energies the spin-split ${p}_{x}{p}_{y} ({m}_{j}=3/2)$ and ${p}_{z}$ bands as well as the first three members of a series of image-potential resonances were observed. Circular dichroism was used to gain information on the spin structure of both the initial and intermediate states and to corroborate the assignment to Rashba bands.