Slomski, BartoszLandolt, GabrielMuff, StefanMeier, FabianOsterwalder, JuergDil, J. Hugo2015-06-232015-06-232015-06-23201310.1088/1367-2630/15/12/125031https://infoscience.epfl.ch/handle/20.500.14299/115346WOS:000330377800002Using spin and angle-resolved photoemission spectroscopy we investigate a momentum region in Pb quantum well states on Si(111) where hybridization between Rashba-split bands alters the band structure significantly. Starting from the Rashba regime where the dispersion of the quasi-free two-dimensional electron gas is well described by two spin-polarized parabolas, we find a breakdown of the Rashba behavior which manifests itself (i) in a spin splitting that is no longer proportional to the in-plane momentum and (ii) in a reversal of the sign of the momentum splitting. Our experimental findings are well explained by including interband spin-orbit coupling that mixes Rashba-split states with anti-parallel rather than parallel spins. Similar results for Pb/Cu(111) reveal that the proposed hybridization scenario is independent on the supporting substrate.text::journal::journal article::research article