Spin-orbit splitting of quantum well states in n -monolayer Ir/Au(111) heterostructures

The effect of spin-orbit coupling on quantum well states (QWSs) in atomically thin Ir adlayers deposited on the Au(111) substrate is studied in the framework of the density functional theory. Varying the Ir film thickness from 1 to 3 atomic layers, we find numerous Ir-derived QWSs, which are mainly of d character. The resulting band dispersion of QWSs appearing around the surface Brillouin zone center in a wide Au(111) energy gap is analyzed in the framework of the Rashba model. In all such QWSs, the fitted values of the Rashba parameter exceed 2eVÅ. The maximal value of 6.4eVÅ was obtained for the 1-monolayer-Ir/Au(111) system. We explain such large spin splitting by hybridization between different QWSs. Strong enhancement is observed in the density of electronic states at the surface in the energy region around the Fermi level caused by these QWSs.
I.V.S. acknowledges the Ministry of Science and Higher Education of the Russian Federation for funding in framework of State Task (No. 0721-2020-0033). Y.M.K. acknowledges the Fundamental Research Program of the State Academies of Sciences, line of research III.23.2.9 and the Tomsk State University competitiveness improvement program (Project No. 8.1.01.2018). V.M.S. acknowledges funding from the Project of the Basque Government (Q-NANOFOT IT1164-19). E.V.C. acknowledges the Saint-Petersburg State University (Project No. 51126254). V.M.S. and E.V.C. acknowledge the Spanish Ministry of Economy, Industry and Competitiveness MINEICO (Projects Nos. FIS2016-76617-P and FIS2016-75862-P).