Giant Rashba-Spin Splitting of Bi(111) Bilayer on Large Band Gap   $\beta-$In$_2$Se$_3$
  Experimentally it is still challenging to epitaxially grow Bi(111) bilayer (BL) on conventional semiconductor substrate. Here, we propose a substrate of $\beta-$In$_2$Se$_3$(0001) with van der Waals like cleavage and large band gap of 1.2~eV. We have investigated the electronic structure of BL on one quintuple-layer (QL) $\beta-$In$_2$Se$_3$(0001) using density functional theory calculation. It is found that the intermediate hybridization between BL and one QL $\beta-$In$_2$Se$_3$(0001) results in the formation of bands with giant Rashba spin splitting in the large band gap of the substrate. Furthermore the Rashba parameter $\alpha_R$ can be increased significantly by tensile strain of substrate. Our findings provide a good candidate substrate for BL growth to experimentally realize spin splitting Rashba states with insignificant effect of spin degenerate states from the substrate. 
Wenmei Ming, Z. F. Wang and Feng Liu
cond-mat.mtrl-sci