Electronic structure of the Pd2Sn surface alloy on Pd(111)-(√3 x √3)R30°

Based on the density functional theory, we have calculated an atomic and electronic structures of the Pd2Sn/Pd(111)-(root 3 x root 3)R30 degrees surface alloy including spin orbit coupling (SOC) effects. In the single layer Pd2Sn surface alloy, Sn segregated structure in which Pd occupies the second layer while Sn floats to the surface is found to be energetically favourable by 0.14 eV. This structure allows alloy formation at the surface in the form of Pd2Sn as suggested by recent experimental study. Considering second internal Pd2Sn alloy layer together with outmost Pd2Sn alloy layer, we have determined out of plane corrugation which has a corrugation value of 0.26 A. In the single layer Pd2Sn surface alloy, the related electronic band structure and characteristic of the surface states have been calculated. An examination of origin of these surface states is mainly contributed by hybridization between s- and p-like orbitals of Sn atom and s-, p-, and d-like orbitals of Pd atom. This surface exhibits smaller Rashba spin splitting, i.e. the amount of split of the surface bands is about 0.05 eV in PBE functional and 0.03 eV in LDA functional within SOC effects.