Kavli Affiliate: Jie Shan
| First 5 Authors: Yiyu Xia, Zhongdong Han, Kenji Watanabe, Takashi Taniguchi, Jie Shan
| Summary:
Moir’e materials have enabled the realization of flat electron bands and
quantum phases that are driven by strong correlations associated with flat
bands. Superconductivity has been observed, but solely, in graphene moir’e
materials. The absence of robust superconductivity in moir’e materials beyond
graphene, such as semiconductor moir’e materials, has remained a mystery and
challenged our current understanding of superconductivity in flat bands. Here,
we report the observation of robust superconductivity in 3.65-degree twisted
bilayer WSe2 which hosts a honeycomb moir’e lattice. Superconductivity emerges
at half-band filling and under small sublattice potential differences, where
the moir’e band is a flat Chern band. The optimal superconducting transition
temperature is about 220 mK and constitutes 2% of the effective Fermi
temperature; the latter is comparable to the value in high-temperature cuprate
superconductors and suggests strong pairing. The superconductor borders on two
distinct metals below and above half-band filling; it undergoes a continuous
transition to a correlated insulator by tuning the sublattice potential
difference. The observed superconductivity on the verge of Coulomb-induced
charge localization suggests roots in strong electron correlations.
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