{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"66599952ccdff5a8833a1a43680b953d6ab2392f8b87f6d0f631fd95efe91b9d","created":"2026-10-15T23:43:22Z","files":[],"origin":{"assisted_by":["ai:gpt-5.5"],"kind":"seed"},"parents":["8b7dad2e733cfc5063fb3039fd55b19f0ae1abb46de61d73e5395f2bd78b440f","ce59fb6cd812fc05906d0c60a71c75ea22bc686bcf38e7c3ef7010834d98ee7b"],"salt":"0bd89bcf7751dbfacf94a1b183aedf254a70a9a3189f3654bdea1454934de766","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"mechanism","assisted_by":["ai:gpt-5.5"],"external_id":"cm.nickelates.infinite-layer-films-only","kind":"phenomenon","literature_status":"contested","n":"2","parents":[],"plain":"Infinite-layer nickelates superconduct when made as thin films but not, so far, as bulk crystals made by the same chemical reduction step.","posed_since":"2019","precise":"Explain why superconductivity in $\\mathrm{R}1-x\\mathrm{Sr}x\\mathrm{NiO}2$ ($R = \\mathrm{La}, \\mathrm{Pr}, \\mathrm{Nd}, \\mathrm{Sm}$) appears in thin films but not in bulk samples made by the same topotactic reduction. Candidates: residual apical oxygen or incorporated hydrogen in bulk, epitaxial strain, interface effects, secondary phases. An answer is a bulk sample with full diamagnetic shielding (filamentary or low-volume-fraction signals do not count), or an identification of the controlling structural or chemical variable.","problem_ref":"8b7dad2e733cfc5063fb3039fd55b19f0ae1abb46de61d73e5395f2bd78b440f","references":"","settled_by":"A bulk or freestanding-membrane sample with full shielding, or a controlled study varying the candidate variable in films that switches superconductivity on and off.","status_note":"Samarium-based infinite-layer films reached about $40\\ \\mathrm{K}$ (2025); a 2026 preprint reports low-volume-fraction, non-percolative superconductivity at ambient pressure in bulk crystals of the related square-planar trilayer nickelates (La,Pr)4Ni3O8 and (La,Y)4Ni3O8, so bulk superconductivity with full shielding is not established.","title":"Why infinite-layer nickelates superconduct only as thin films","topic_ref":null},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"ffe1fe4f32e747c4ccfbfef983e5b588b6dfa0252749e800d127b2f8080f2674","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"deb40ff84e89cdec26d3452d875244f507f044b2cb476640a841bd4d10ebc74f","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"NaTMvF0-oNnC4nH_xeFgdjJzJ0ejy7JeCWVyoKieYIc6HlXWqlJRrwdnapF69u62wVpjh9MnpInvyQkr_MWoAw"},"schema":"pubphys.envelope/1"},"record_hash":"ffe1fe4f32e747c4ccfbfef983e5b588b6dfa0252749e800d127b2f8080f2674","leaf_index":2970}