Controlling the effective mass and Rashba-type spin splitting in Pb quantum well states

Full text: When the thickness of an ultra-thin film, such as Pb on Si(111), approaches the electron coherence length, quantum well states (QWS) may form. These states can be described as standing waves confined perpendicular to the surface due to the global band gap of Si(111) and due to the image potential at the metal/vacuum interface. Because of lack of translation symmetry perpendicular to the surface these electronic states become spin split according to the Rashba model. The strength of the spin splitting arises from the asymmetry of the charge density around the Pb nuclei. This opens up the possibility to control the splitting by shifting the charge density in the metal by inducing different potential barriers at the metal-to-substrate interface. Here we will show by spin and angle resolved photoemission experiments how a change of the interface from Pb to Bi influences the band dispersion and spin texture of the Pb overlayer. These findings can provide a further step towards the design of spintronic applications, especially since the metal layers are grown on silicon substrates (author)