Tunable valley band and exciton splitting by interlayer orbital hybridization

Abstract

AbstractMagnetic proximity effect has been demonstrated to be an effective routine to introduce valley splitting in two-dimensional van der Waals heterostructures. However, the control of its strength and the induced valley splitting remains challenging. In this work, taking heterobilayers combining monolayer MSe2 (M = Mo or W) with room-temperature ferromagnetic VSe2 as examples, we demonstrate that the valley splitting for both band edges and excitons can be modulated by the tuning of the interlayer orbital hybridization, achieved by inclusion of different amounts of exact Hartree exchange potential via hybrid functionals. Besides, we show such tuning of orbital hybridization could be experimentally realized by external strain and electric field. The calculations suggest that large valley band splitting about 30 meV and valley exciton splitting over 150 meV can be induced in monolayer MSe2. Our work reveals a way to control proximity effects and provides some guidance for the design of optoelectronic and valleytronic devices.