Higher-order contributions to the Rashba-Bychkov effect with application   to Bi/Ag(111) surface alloy
  In order to explain the anisotropic Rashba-Bychkov effect observed in several metallic surface-state systems, we use k.p perturbation theory with a simple group-theoretical analysis and construct effective Rashba Hamiltonians for different point groups up to third order in the wavenumber. We perform relativistic ab initio calculations for the Bi/Ag(111) ordered surface alloy and from the calculated splitting of the band dispersion we find evidence of the predicted third-order terms. Furthermore, we derive expressions for the corresponding third-order Rashba parameters to provide a simple explanation to the qualitative difference concerning the Rashba-Bychkov splitting of the surface states at Au(111) and Bi/Ag(111). 
Sz. Vajna, E. Simon, A. Szilva, K. Palotas, B. Ujfalussy, L. Szunyogh
cond-mat.mes-hall