{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"bdfce4ff93a1b7a19a93a9ae187af448b58f8e9d57d0e5d0c9d8d09860db7c9a","created":"2026-10-03T07:18:00Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"b445855b8aadcd4b5a5758e8d4ab0181ca4f6a64a9f4c0e478db9c4d390c6ae8","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":"1","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 $k_B \\operatorname{ln} 2$ 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":null,"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":"5046e808e6fff9aacad641f2a7f962b0712731127198d6ca10149f1ce640621c"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"2ad0ad632a5504dd6de6088f7c4462562e18f3133c367d832c92b55b9682f639","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"bb6c7dc2baab3800a7ec012c984dcab3704f629dc1784c66068088ae95019347","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"XJQPZxMdIMGV5Y85SI0VJqluWKptD55HR1ZR0_BKkW_h__oqo7hbb_lYkS_7i9eMJh504eCdKf4BVKzyI2EmDw"},"schema":"pubphys.envelope/1"},"record_hash":"2ad0ad632a5504dd6de6088f7c4462562e18f3133c367d832c92b55b9682f639","leaf_index":1071}