Optical Response of Transition-Metal Dichalcogenides with Trigonal Warping and Rashba Spin-Orbit Coupling

The optical response with spin-valley coupling in monolayer transition-metal dichalcogenides (TMDs), often dominated by tightly bound excitons, provides a valuable probe for their inherent properties and the properties of van der Waals heterostructures. For example, unlike in the widely-studied magnetic proximity effects that are typically limited to the single-particle picture in many materials, in TMDs the key fingerprint of magnetic proximity is contained in the modification of their excitons [1]. Such excitons reveal a removal of valley degeneracy in TMDs [2,3] and show the changes in the optical selection rules with noncolinear orientation between the magnetization of a substrate and the intrinsic spin-orbit field [1]. While the necessity of an accurate many-body description for TMDs is now recognized [2,3], the role of trigonal warping and Rashba spin-orbit coupling on optical properties remains unexplored. By carefully solving the Bethe-Salpeter equation, we study both their individual and combined effects in optical absorption and discuss how they can be observed experimentally.

[1] B. Scharf et al., Phys. Rev. Lett. 119, 127403 (2017)

[2] I. Zutic et al., Mater. Today 22, 85 (2019)

[3] J. F. Sierra et al., Nat. Nanotechnol. 16, 856 (2021)