First-principles Study of Rashba Effect in Ultra-thin Bismuth Surface Alloys

We performed density functional calculations for ultra-thin bismuth surface alloys: surface alloys of bismuth and face-centered cubic metals Bi/$M$(111)-$(\sqrt{3}\times \sqrt{3})R30\mathrm{deg}$ ($M$=Cu, Ag, Au, Ni, Co, and Fe). Our calculated Rashba parameters for the Bi/Ag are consistent with the previous experimental and theoretical results. We predicted a trend in the Rashba coefficients ${\alpha }_R$ of bands around the Fermi energy for noble metals as follows: Bi/Ag > Bi/Cu > Bi/Au. As for the transition metals, there is a trend in ${\alpha }_R$: Bi/Ni > Bi/Co > Bi/Fe. Our finding may lead to design efficient spin-charge conversion materials.