Ag growth on the Ag2Bi Rashba alloy

Multilayer structures comprising Bi/Ag bilayers display spin-charge conversion, a phenomenon of interest in spintronics whose origin (inverse Rashba-Edelstein vs. inverse spin Hall effects) is still debated. The Bi/Ag interfaces are assumed to be stable in model calculations, but the experimental determination of their structural properties is missing. Here, we explore by photoemission spectroscopy the stability and electronic structure of a Bi/Ag interface with strong Rashba interaction. We saturate the surface of a Ag(111) crystal with the AgBi alloy, which presents surface-embedded Bi atoms and characteristic Rashba-split surface states, and deposit Ag layers on top of it at room temperature. The intensity of the Rashba-split bands weakens sizably after the deposition of few Ag monolayers, although most of the Bi atoms segregate at the surface and retain the original local coordination. These findings are consistent with the surfactant behavior of Bi atoms, which favors a layer-by-layer Ag growth without preserving the long-range order of the AgBi alloy. They also suggest the need of detailed chemical and structural analysis for an accurate description of Bi/Ag bilayers.