{"schema":"pubphys.bundle/1","record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"61d8a355b93389300cd33f36cd8d26310f1c2efeed2c11b16d2acfe1baa089ff","created":"2026-10-03T07:18:00Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"65b9e929bd5c3f72a8844792df103e1abcdec9db53cc4ebfaa2f9f73522c8657","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"yes-no","assisted_by":[],"external_id":"cm.mit-2d-electrons.zero-temperature-metal","kind":"well-posed","literature_status":"contested","n":"1","parents":[],"plain":"Scaling theory says a thin disordered sheet of non-interacting electrons is always an insulator at absolute zero. The question is whether strong repulsion allows a true metal, or whether the observed metal turns insulating at temperatures not yet reached.","posed_since":"1994","precise":"For 2D electrons with $1/r$ Coulomb repulsion and weak short-range disorder at $r_s >> 1$, determine whether $\\sigma(T \\to 0) > 0$ in a finite density range $n > n_{c}$, implying a quantum phase transition at $n_{c}$ with scaling $\\rho(n, T) = F(\\mid n - n_{c}\\mid / T^{(1/(z \\nu))})$, or whether $\\rho(T)$ eventually rises (logarithmically or faster) at every $n$. An answer gives the $T = 0$ phase diagram in $(n, \\mathrm{disorder})$, or the crossover temperature $T*(n, \\mathrm{disorder})$ below which localization appears.","problem_ref":null,"references":"","settled_by":"Transport down to T well below $0.01 E_{\\mathrm{F}}$ in samples with independently calibrated weak-localization and interaction corrections, or a controlled theory of the disordered interacting 2D electron gas at $r_s >> 1$.","status_note":"","title":"Does a two-dimensional metal survive to zero 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