Proximity control of interlayer exciton-phonon hybridization in van der Waals heterostructures

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P. Merkl, C.-K. Yong, M. Liebich, I. Hofmeister, G. Berghäuser, E. Malic, R. Huber

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Nature Communications

Van der Waals stacking has provided unprecedented flexibility in shaping many-body interactions by controlling electronic quantum confinement and orbital overlap. Theory has predicted that also electron-phonon coupling critically influences the quantum ground state of low-dimensional systems. Here we introduce proximity-controlled strong-coupling between Coulomb correlations and lattice dynamics in neighbouring van der Waals materials, creating new electrically neutral hybrid eigenmodes. Specifically, we explore how the internal orbital 1s-2p transition of Coulomb-bound electron-hole pairs in monolayer tungsten diselenide resonantly hybridizes with lattice vibrations of a polar capping layer of gypsum, giving rise to exciton-phonon mixed eigenmodes, called excitonic Lyman polarons. Tuning orbital exciton resonances across the vibrational resonances, we observe distinct anticrossing and polarons with adjustable exciton and phonon compositions. Such proximity-induced hybridization can be further controlled by quantum designing the spatial wavefunction overlap of excitons and phonons, providing a promising new strategy to engineer novel ground states of two-dimensional systems.

P. Merkl, C.-K. Yong, M. Liebich, I. Hofmeister, G. Berghäuser, E. Malic, R. Huber, Nature Communications
12, 1719 (2021)

https://www.nature.com/articles/s41467-021-21780-6
https://www.uni-regensburg.de/pressearchiv/pressemitteilung/1103304.html