A. J. Campbell, M. Brotons-Gisbert, H. Baek, V. Vitale, T. Taniguchi, K. Watanabe, J. Lischner, and B. D. Gerardot, Strongly correlated electronic states in a Fermi sea spatially pinned by a MoSe2/WSe2 moiré superlattice, http://arxiv.org/abs/2202.08879
Two-dimensional moiré materials provide a highly tunable platform to investigate strongly correlated electronic states. Such emergent many-body phenomena can be optically probed in moiré systems created by stacking two layers of transition metal dichalcogenide semiconductors: optically injected excitons can interact with itinerant carriers occupying narrow moiré bands to form exciton-polarons sensitive to strong correlations. Here, we investigate the many-body interactions between excitons and a Fermi sea that is spatially pinned by the moiré superlattice of a molybdenum diselenide (MoSe2) / tungsten diselenide (WSe2) twisted hetero-bilayer. At a multitude of fractional fillings of the moiré lattice, we observe ordering of both electrons and holes into stable correlated electronic states. Magneto-optical measurements reveal extraordinary Zeeman splittings of the exciton-polarons due to exchange interactions between holes in the correlated phases, with a maximum close to the correlated state at one hole per site. The temperature dependence of the Zeeman splitting reveals antiferromagnetic ordering of the correlated holes across a wide range of fractional fillings. Our results illustrate the nature of excitons interacting with a spatially pinned Fermi sea and provide robust evidence for strongly correlated electronic states in MoSe2/WSe2 hetero-bilayers, unveiling the rich potential of this platform for investigations of Fermi-Hubbard and Bose-Hubbard physics.