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Title: Quantum melting of generalized Wigner crystals in moire semiconductors
Plain: At fractional fillings such as one electron per three moire sites, electrons in WSe2/WS2 order into crystals because of their repulsion (generalized Wigner crystals), and how these crystals turn into metals as the repulsion is weakened is unknown.
Precise: In WSe2/WS2 and similar heterobilayers, insulating states at fractional fillings $\nu = 1/3, 1/2, 2/3$ and others were detected optically (Regan et al., Nature, 2020, arXiv:1910.09047) and later imaged. As the ratio of Coulomb energy to bandwidth, or the screening length set by gate distance, is reduced, determine whether each crystal melts into a Fermi liquid directly (first or second order) or through intermediate phases such as stripes, bubbles, microemulsions or a quantum-melted state without charge order but with insulating transport. An answer is a phase diagram versus $\nu$ and screening length with the order of each transition.
Settled by: Local imaging of charge order versus gate distance and density, with compressibility measurements locating each transition and its hysteresis.
Kind: well-posed
Answer type: classification
References: (empty)
Literature status: open
Status note: (empty)
Posed since: 2020