SKM 2023 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 34: 2D Materials V (joint session HL/CPP)

HL 34.9: Talk

Thursday, March 30, 2023, 11:45–12:00, POT 81

Microscopic picture of interlayer exciton-phonon coupling — Muralidhar Nalabothula, Ludger Wirtz, and •Sven Reichardt — University of Luxembourg, Luxembourg

Excitons play a key role for opto-electronic applications of 2D heterostructures. They also can strongly couple to phonons as evidenced by their imprint on resonant Raman scattering intensities [1,2]. In 2D heterostructures, this sort of strong coupling and its signature Raman scattering offers an ideal setting to learn about exciton-phonon coupling both within and across material layers. Here we focus on the example of monolayer WSe2 and hBN. Its Raman spectrum features the norminally silent out-of-plane optical phonon mode of hBN that becomes active due to symmetry breaking and - most curiously - very strongly enhanced due to resonant exciton-phonon scattering [1]. While the resonant scattering pathways have been identified as involving excitons in WSe2 that couple to the phonons in hBN [1], a microscopic understanding of this interlayer exciton-phonon coupling is still missing. We provide such understanding using the state-of-the-art method for the computation for resonant Raman scattering intensities [2,3], which allows a detailed atomistic and quantum mechanical dissection of the Raman scattering process. Supplemented by a classical picture, our work sheds light on the microscopic mechanism behind exciton-phonon coupling in 2D heterostructures.

[1] C. Jin, et al. Nat. Phys., 13, 127-131, (2017).

[2] S. Reichardt and L. Wirtz. Sci. Adv. 6, eabb5915, (2020).

[3] S. Reichardt and L. Wirtz. Phys. Rev. B 99, 174312, (2019).