Proximity Effects and Excitons in Van der Waals Heterostructures

Excitonic spectra of 2D semiconductors are known to be very sensitive to the dielectric surroundings. But they can also be tailored<br/>by weak van der Waals hybridizations across the layers---the so called proximity effects. Placing a transition metal dichalcogenide, such<br/>as WSe2, in contact with a ferromagnetci CrI3, results in exchange induced valley-resolved single-particle spectral shifts which can be<br/>probed by excitonic absorption. I will present our theoretical efforts in ab initio modeling of the proximity effects and the Bethe-Salpeter equation simulation of the excitonic spectra affected by the proximity. I will also argue that in addition to pure dielectric screening effects, there are also hybridization signitures in the g-factor of excitons in transition metal dichalcogenides in contact with graphene. Finally, I will present an analysis of the excitonic g-factors in strained TMDCs in which a hybridization between inter and intraband transistions can be tuned by strain.<br/>Support from DFG SFB 1277, SPP2244, and FLAG-ERA is acknoweldged.<br/><br/>PEF Junior et al,<i> First-principles insights into the spin-valley physics of strained transition metal dichalcogenides monolayers</i>, New J. Phys. 24, 083004 (2022).<br/>E Blundo et al, Strain-Induced Exciton Hybridization in WS2 Monolayers Unveiled by Zeeman-Splitting Measurements, Phys. Rev. Lett. 129, 067402 (2022).<br/>FS Covre et al, <i>Revealing the impact of strain in the optical properties of bubbles in monolayer MoSe2</i>, Nanoscale 14, 5758 (2022).<br/>K Zollner et al, <i>Strong manipulation of the valley splitting upon twisting and gating in MoSe2/Cr3 and WSe2/Cr3 van der Waals heterostructures</i>, Phys. Rev. B 107, 035112 (2023).<br/>PEF Junior et al, <i>Proximity-enhanced valley Zeeman splitting at the WS₂/graphene interface, </i>2D Materials, 10, 034002 (2023).