Giant Rashba-Spin Splitting of Bi(111) Bilayer on Large Band Gap $\beta-$In$_2$Se$_3$

TL;DR

This study proposes using $eta$-In$_2$Se$_3$ as a substrate for Bi(111) bilayer growth, demonstrating giant Rashba spin splitting through density functional theory, with tunability via tensile strain, advancing spintronic applications.

Contribution

It introduces $eta$-In$_2$Se$_3$ as a promising substrate for Bi(111) bilayer growth, enabling large Rashba spin splitting with strain-tunable properties.

Findings

Giant Rashba spin splitting observed in Bi(111) bilayer on $eta$-In$_2$Se$_3$

Rashba parameter $eta_R$ can be significantly increased by tensile strain

Substrate provides a platform for experimental realization of spin splitting states

Abstract

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.