Giant and tunable Rashba spin splitting in MoS2/Bi2Te3 heterostructures

Abstract

The study of the spin-orbit coupling (SOC) effect is an active research field in physics and it is of great interest for materials with large Rashba spin splitting (RSS) in spintronics applications. In this report, based on first-principles calculations, we propose the heterostructure of MoS2/Bi2Te3 with giant RSS duo to the lack of spatial inversion symmetry and the intrinsic electric field perpendicular to the heterostructure. Furthermore, it is found that the electronic and RSS can be tuned effectively by layers of MoS2 and Bi2Te3. When the Bi2Te3 thickness is less than 2QL, these MoS2/Bi2Te3 heterojunction systems exhibit semiconductor properties. The magnitude of the RSS in these MoS2/Bi2Te3 heterojunctions changes with the thickness, and the largest band splitting is found in the (MoS2)1(Bi2Te3)2 heterostructure with a Rashba coefficient of ~2.5 eV Å, which is a very large value among two-dimensional (2D) materials. While the interlayer distance and charge transfer remain stable at about 3.5 Å and 0.1 e, respectively. Through layer-projected band structure analysis, it is proven that the electronic states of these quantum well states (QWSs) are mainly contributed by Bi2Te3, while the MoS2 layer only plays an inductive role and does not contribute to the QWSs electrons. In addition, strain only plays a minor role in the Rashba effect in the MoS2/Bi2Te3 heterojunction, which is mainly caused by the breaking of the spatial inversion symmetry. The giant and tunable Rashba-type SOC of the MoS2/Bi2Te3 heterostructure suggests that it is a type of promising materials for spintronic applications.