Using spin- and angle-resolved photoemission spectroscopy we show that the spin splitting and the spin texture of quantum well states in thin Pb films can be manipulated through changes in the interface to the substrate. Compared with films grown on the Pb reconstructed Si(111) substrate the Bi interface reduces the spin splitting of the Pb states by a factor of 2 and the spin polarization vector is rotated by 32∘ out of the sample plane. The spin splitting on an Ag reconstructed substrate is below the experimental resolution. Based on a model supported by ab initio calculations we interpret these changes as due to a modification of the charge density distribution in the quantum well states.
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