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arXiv · 2105.03997

Observation of electrically tunable Feshbach resonances in twisted bilayer semiconductors

Ido Schwartz·Yuya Shimazaki·Clemens Kuhlenkamp·Kenji Watanabe·Takashi Taniguchi·Martin Kroner·Ataç Imamoğlu
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Abstract

Moire superlattices in twisted transition metal dichalcogenide bilayers have emerged as a rich platform for exploring strong correlations using optical spectroscopy. Despite 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 ensured a classical layer degree of freedom in these experiments. Here, we investigate a MoSe$_2$ homobilayer structure where inter-layer coherent tunnelling and layer-selective optical transitions allow for electric field controlled manipulation and measurement of the layer-pseudospin of the ground-state holes. A striking example of qualitatively new phenomena in this system is our observation of an electrically tunable 2D Feshbach resonance in exciton-hole scattering, which allows us to control the strength of interactions between excitons and holes located in different layers. Our findings enable hitherto unexplored possibilities for optical investigation of many-body physics, as well as realization of degenerate Bose-Fermi mixtures with tunable interactions, without directly exposing the itinerant fermions to light fields.

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Ido Schwartz, Yuya Shimazaki, Clemens Kuhlenkamp, Kenji Watanabe, Takashi Taniguchi, Martin Kroner, Ataç Imamoğlu. 2021-05-09. Observation of electrically tunable Feshbach resonances in twisted bilayer semiconductors. https://doi.org/10.1126/science.abj3831

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