{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"a3b12877b45eb7a14e074b4aca4a36d2981167d2831e178de76ce41e1f4a7a9f","created":"2026-10-15T23:43:22Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["2ad0ad632a5504dd6de6088f7c4462562e18f3133c367d832c92b55b9682f639","ce59fb6cd812fc05906d0c60a71c75ea22bc686bcf38e7c3ef7010834d98ee7b"],"salt":"58a34c81ea8e989b262b4084906634b527ddc4784257233392376ac838f9b2ae","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"yes-no","assisted_by":[],"external_id":"cm.magic-angle-graphene.heavy-fermion-picture","kind":"phenomenon","literature_status":"contested","n":"2","parents":[],"plain":"One theory describes the flat-band electrons of magic-angle graphene as magnetic moments localized at particular spots of the moire pattern, mixed with fast conduction electrons as in heavy-fermion metals, and whether experiments confirm this picture is debated.","posed_since":"2021","precise":"Song and Bernevig (PRL 129, 047601, 2022, arXiv:2111.05865) mapped the continuum model of magic-angle twisted bilayer graphene onto localized f-orbitals at AA-stacked regions hybridized with topological dispersive c-electrons. Determine whether experiments at $\\nu = 0\\ \\text{to}\\ \\pm 3$ show the defining features of this picture: Curie-like local-moment susceptibility and moment entropy of order $k_B \\ln 2$ per moire cell at $T \\sim 10\\,\\mathrm{K}$, a coherence temperature below which the moments are screened, and a hybridization gap or Kondo-like resonance in tunnelling at AA sites. An answer is yes or no, based on measured coherence temperature, moment entropy and spectral weight compared with the model parameters.","problem_ref":"2ad0ad632a5504dd6de6088f7c4462562e18f3133c367d832c92b55b9682f639","references":"","settled_by":"Tunnelling spectroscopy resolving a temperature-dependent hybridization feature at AA sites, together with thermodynamic measurement of the moment entropy and its quenching below a coherence temperature.","status_note":"Large magnetic entropy consistent with fluctuating moments was reported in 2021, but whether a Kondo coherence scale exists is debated as of 2026, to this survey's knowledge.","title":"Is magic-angle graphene a topological heavy-fermion system?","topic_ref":null},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"2b3c718d46eff100b052567c09adbaeb7d4f4f232751fe10018c2c721584db5f","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"aaced12f9e3218221e359ed60f58c96a5fd269c37003d5a6591ed7a14f54c10c","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"xBgyzkM3yvj4hK5UknyjcuS8TDxx5z8tcltQBsbM6Vho596QdQvOcWl6VlbQbaux0DeuWkeVfIdp36zCzXE9CA"},"schema":"pubphys.envelope/1"},"record_hash":"2b3c718d46eff100b052567c09adbaeb7d4f4f232751fe10018c2c721584db5f","leaf_index":2914}