k -asymmetric spin-splitting at the interface between transition metal ferromagnets and heavy metals.

We systematically investigate the spin-orbit coupling-induced band splitting originating from inversion symmetry breaking at the interface between a Co monolayer and 4 d (Tc, Ru, Rh, Pd, and Ag) or 5 d (Re, Os, Ir, Pt, and Au) transition metals. In spite of the complex band structure of these systems, the odd-in- k spin splitting of the bands displays striking similarities with the much simpler Rashba spin-orbit coupling picture. While we do not find salient correlations between the interfacial magnetic anisotropy and the odd-in- k spin-splitting of the bands, we establish a clear connection between the overall strength of the band splitting and the charge transfer between the d -orbitals at the interface. Furthermore, we show that the spin splitting of the Fermi surface scales with the induced orbital moment, weighted by the spin-orbit coupling.