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Title: How does the field-induced Wigner crystal melt into quantum Hall liquids?
Plain: A strong perpendicular magnetic field shrinks electron orbits and favors a crystal at low filling, but fractional quantum Hall liquids compete with it. How the system passes between the two, and whether unusual intermediate states appear, is open.
Precise: In high-mobility GaAs and graphene 2D systems at Landau-level filling $\nu$ between $1/7$ and $1/3$, insulating phases interpreted as pinned Wigner crystals reenter between fractional quantum Hall states, e.g. near $\nu = 1/5$. Determine the $T = 0$ phase diagram in $(\nu, r_s)$ including Landau-level mixing, the order of the crystal to liquid transitions, and whether intermediate phases (Hall crystals, crystals of composite fermions) exist.
Settled by: Local imaging and thermodynamic measurements across $\nu$ near $1/5$, matched to variational or DMRG calculations that include Landau-level mixing.
Kind: well-posed
Answer type: classification
References: (empty)
Literature status: open
Status note: Scanning tunneling microscopy in Bernal bilayer graphene directly imaged a magnetic-field-induced Wigner crystal (Tsui et al., Nature 628, 287, 2024); its transitions to neighboring quantum Hall liquids are under study.
Posed since: (empty)