Spin-orbit coupling in low-dimensional gold

We present experimental and theoretical evidence of the role played by the spin–orbit coupling in the electronic structure of a pseudomorphic Au monolayer on Nb(001) substrate. The bands found with the help of the angle‐resolved ultraviolet photoelectron spectroscopy (ARUPS) are compared with those obtained from ab initio self‐consistent calculations by the VASP and WIEN2k codes. The slab calculations are performed including geometric relaxation and using both the generalized‐gradient (GGA) and local‐density (LDA) approximations for the exchange–correlation energy. The dispersions and energy positions of the calculated bands agree with the experimentally determined band structure only if the LDA is used and the spin–orbit coupling is included. Therefore, both the structure relaxation and spin–orbit coupling are essential in understanding the electronic structure of the Au/Nb(001) system. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) The article offers a fresh example for the significance of spin‐orbit coupling in low dimensional gold – a system with potential relevance in the form of atomic wires or other nanostructures. By a combined experimental and theoretical study of the electronic band structure of a peculiar Au monolayer grown on a Nb(001) surface, it is found that spin‐orbit coupling as well as the structural relaxation are essential ingredients for an accurate description of the valence electronic behaviour in this special low‐dimensional system.