Rashba effect at magnetic surfaces and interfaces

Full text: A key issue of condensed matter research for future spintronic devices is the control and manipulation of the electron spin without the need to apply an external magnetic field. In a combined experimental and theoretical study, employing valence band photoemission and ab initio band structure calculations we demonstrate, at the examples of ferromagnetic rare earth Gd(0001) and Tb(0001) surfaces, that (1) the Rashba spin-orbit effect is a general surface and interface phenomenon which, in case of d-derived surface (interface) states, can lead to substantial Rashba splittings, and that (2) the Rashba splitting of d-derived surface states is strongly enhanced when an epitaxial metal oxide layer is formed on top of a metal surface. The experimental observations are quantitatively described by ab initio calculations giving a detailed account of the near-surface charge density gradients. They show that the enhanced Rashba interaction upon oxide layer formation is caused by a spread of the two-dimensional states over a wider interface lattice region, together with a substantial change in orbital character