Direct band gap and strong Rashba effect in van der Waals heterostructures of InSe and Sb single layers

TL;DR

This study demonstrates that InSe/Sb van der Waals heterostructures possess a direct band gap and significant Rashba spin splitting, which can be tuned by strain and electric fields, making them promising for spintronic and optoelectronic devices.

Contribution

First-principles analysis revealing stable InSe/Sb heterostructures with tunable Rashba effect and direct band gap, advancing potential applications in spintronics and optoelectronics.

Findings

Heterostructures exhibit a direct band gap regardless of stacking pattern.

Large Rashba spin splitting is present and tunable by strain and electric field.

Potential for use in spin field-effect transistors and optoelectronic devices.

Abstract

Van der Waals heterostructures formed by stacking different types of 2D materials are attracting increasing attention due to new emergent physical properties such as interlayer excitons. Recently synthesized atomically thin indium selenide (InSe) and antimony (Sb) individually exhibit interesting electronic properties such as high electron mobility in the former and high hole mobility in the latter. In this work, we present a first-principles investigation on the stability and electronic properties of ultrathin bilayer heterostructures composed of InSe and Sb single layers. The calculated electronic band structures reveal a direct band gap semiconducting nature of the InSe/Sb heterostructures independent of stacking pattern. Taking spin-orbit coupling into account, we find a large Rashba spin splitting at the bottom of conduction band, which originates from the atomic spin-orbit coupling with the symmetry breaking in the heterostructure. The strength of the Rashba spin splitting can be tuned by applying in-plane biaxial strain or an out-of-plane external electric field. The presence of large Rashba spin splitting together with a suitable band gap in InSe/Sb bilayer heterostructures make them promising candidates for spin field-effect transistor and optoelectronic device applications.