Magnetization-dependent Rashba splitting of quantum well states at the Co/W interface

Exchange and Rashba spin-orbit interactions are expected to couple at ferromagnetic-metal/heavy-metal interfaces and influence their electronic structure. We examine these largely unexplored effects in Co(0001) films on W(110) by angle-resolved photoemission spectroscopy. We find breaking of inversion symmetry in the band dispersion of magnetic quantum well states along structurally equivalent directions of the Co films. Ab initio calculations ascribe this unusual band behavior to the relative orientation of coexisting exchange and Rashba fields. These findings elucidate fundamental interface electronic effects, which are associated to spin-orbit phenomena at ferromagnetic-metal/heavy-metal junctions.