Transport Properties of Co in Cu(100) from Density Functional Theory Calculations

The electronic transport properties of a point contact system formed by a single Co atom adsorbed on Cu (100) and contacted by a copper tip is evaluated in the presence of intra-atomic Coulomb interactions and spin orbit coupling. The calculations are performed using equilibrium Green's functions evaluated within density functional theory completed with a Hubbard U term and spin orbit interaction, as implemented in the Gollum package. We show that the contribution to the transmission between electrodes of spin flip components is negative and scaling as lambda(2)/Gamma(2) where lambda is the SOC and Gamma the Co atom-electrode coupling. Hence, due to this unfavorable ratio, SOC effects in transport in this system are small. However, we show that the spin-flip transmission component can increase by 2 orders of magnitude depending on the value of the Hubbard U term. These effects are particularly important in the contact regime because of the prevalence of d-electron transport, while in the tunneling regime, transport is controlled by the sp-electron transmission, and results are less dependent on the values of U and SOC. Using our electronic structure and the elastic transmission calculations, we discuss the effect of U and SOC on the well-known Kondo effect of this system.