Manipulation of optical response in transition metal dichalcogenides by magnetic proximity effects and strain

Efficient manipulation of the optical response of two-dimensional (2D) semiconductors, dominated by excitons due to strong electron-hole Coulomb attraction, could give rise to both discoveries of emergent phenomena and implementation of optoelectronic devices. We propose a manipulation of the optical response of 2D semiconductors through combining magnetic proximity effects and strain, using a Janus type of monolayer (ML) transition-metal dichalcogenides (TMDs) for numerical illustration. Based on an effective Hamiltonian of a strained ML MoSSe on a magnetic substrate and a Bethe-Salpeter equation for an accurate description of excitons, we predict a mergence of $A$ and $B$ excitons at a critical strength of in-plane magnetic exchange field. Additionally, an enhanced tunability of the optical absorption spectra is demonstrated via the combination of magnetic exchange fields and strain. Our approach could be generally extended to other 2D semiconductors subject to magnetic proximity effects and strain.