Peculiar electron-phonon coupling in hBN/WS₂ heterostructures

The electron-phonon coupling (EPC) in materials is the key to the fundamental research, underlying many novel quantum behaviors. van der Waals heterostructures (vdWHs) provide new platform to reveal the intrinsic interactions between electrons and phonons. Here we report the cross-dimensional EPC between the three-dimensional (3D) layer-breathing (LB) phonons in a thick hBN/WS₂ vdWH up to hundreds of layers and two-dimensional (2D) electrons of its few-layer WS₂ constituent. New LB modes are resonantly enhanced in hBN/WS₂ vdWHs when the excitation energy approached the C exciton energy of WS₂ constituent. This cross-dimensional EPC strength is consistent with the phonon wavefunction projection between the layer-extended bulk-like LB modes in hBN/WS₂ vdWHs and the LB modes strongly coupled with the C exciton in the corresponding standalone WS₂ flakes, which can be further confirmed by the interlayer bond polarizability model in vdWHs. This work suggests additional possibilities to manipulate EPC in vdWHs for new quantum phenomena.

Reference:
M.-L. Lin^#, Y. Zhou^#, et al, Nat. Commun. 2019, 10, 2419