{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"071e572db625c3e4444f34b70de59d221d53238c46dc6fd97018d31749de6ef2","created":"2026-10-03T07:18:00Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"1a5bf0109b92871048e9c3cc13a14d56cd5c9e8dcfd3e23f4fc44f1d360812e0","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"mechanism","assisted_by":[],"external_id":"cm.nickelates.infinite-layer-films-only","kind":"phenomenon","literature_status":"contested","n":"1","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":null,"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 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":"1addbb7974855cb74617281e1add5f43c41622b4152f1b5d331c3da3827c5d62"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"8b7dad2e733cfc5063fb3039fd55b19f0ae1abb46de61d73e5395f2bd78b440f","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"4f47d057d8e9bf438ec3e7b70bf53da7da63980e98a8f228bcbef75b4024c87d","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"f3qZxr49bj8Wh5yXmPiXKCzAKftOPezglRGrJpDPjjqcPZXocdmIm6BsCqbcg9HeQwPJiIHyllP-I7KWNh4tBg"},"schema":"pubphys.envelope/1"},"record_hash":"8b7dad2e733cfc5063fb3039fd55b19f0ae1abb46de61d73e5395f2bd78b440f","leaf_index":1110}