2024/07/24 by Liu, Zhida, Wang, Haonan, Liu, Xiaohui +15
#FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci) #Mesoscale and Nanoscale Physics (cond-mat.mes-hall) #Strongly Correlated Electrons (cond-mat.str-el)
paper · doi:10.48550/arxiv.2407.17025
Many fascinating properties discovered in graphene and transition metal dichalcogenide (TMD) moiré superlattices originate from flat bands and enhanced many-body effects. Here, we discover new many-electron excited states in TMD homobilayers. As optical resonances evolve with twist angle and doping in MoSe2 bilayers, a unique type of ``charge-transfer" trions is observed when gradual changes in atomic alignment between the layers occur. In real space, the optically excited electron-hole pair mostly resides in a different site from the doped hole in a moiré supercell. In momentum space, the electron-hole pair forms in the single-particle-band K-valley, while the hole occupies the Γ-valley. The rich internal structure of this trion resonance arises from the ultra-flatness of the first valence band and the distinct influence of moiré potential modulation on holes and excitons. Our findings open new routes to realizing photon-spin transduction or implementing moiré quantum simulators with independently tunable fermion and boson densities.