Electrically tunable Feshbach resonances in twisted bilayer semiconductors.

Schwartz, Ido; Shimazaki, Yuya; Kuhlenkamp, Clemens; Watanabe, Kenji; Taniguchi, Takashi; Kroner, Martin; Imamoğlu, Ataç · Science · 2021

basic_science · Level V

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Abstract

Moiré superlattices in transition metal dichalcogenide bilayers provide a platform for exploring strong correlations with optical spectroscopy. Despite the observation of rich Mott-Wigner physics stemming from an interplay between the periodic potential and Coulomb interactions, the absence of tunnel coupling–induced hybridization of electronic states has ensured a classical layer degree of freedom. We investigated a MoSe<sub>2</sub> homobilayer structure where interlayer coherent tunneling allows for electric field–controlled manipulation and measurement of the ground-state hole-layer pseudospin. We observed an electrically tunable two-dimensional Feshbach resonance in exciton-hole scattering, which allowed us to control the strength of interactions between excitons and holes located in different layers. Our results may enable the realization of degenerate Bose-Fermi mixtures with tunable interactions.