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Resonantly enhanced moir\'e superlattice coupling in heterostructures and transition-metal dichalcogenide bilayers with matching band edges

Research paper by David A. Ruiz-Tijerina, Vladimir I. Fal'ko

Indexed on: 24 Sep '18Published on: 24 Sep '18Published in: arXiv - Physics - Mesoscopic Systems and Quantum Hall Effect



Abstract

Geometrical moir\'e patterns, generic for almost aligned bilayers of two-dimensional (2D) crystals with similar lattice structure but slightly different lattice constants, lead to zone folding and miniband formation for electronic states. Here, we show that moir\'e superlattice (mSL) effects in MoSe${}_2$/WS${}_2$ and MoTe${}_2$/MoSe${}_2$ heterobilayers that feature alignment of the band edges are enhanced by resonant interlayer hybridization. Such hybridization determines the optical activity of interlayer excitons in transition-metal dichalcogenide (TMD) heterostructures, as well as energy shifts in the exciton spectrum. We show that the resonantly hybridized exciton (hX) energy should display a sharp modulation as a function of the interlayer twist angle, accompanied by additional spectral features caused by umklapp electron-photon interactions. We analyze the appearance of resonantly enhanced mSL features in absorption and emission of light by the interlayer exciton hybridization with both intralayer A and B excitons in MoSe${}_2$/WS${}_2$, MoTe${}_2$/MoSe${}_2$, MoSe${}_2$/MoS${}_2$, and WSe${}_2$/MoS${}_2$, and anticipate similar features in twisted homobilayers of TMDs.