{"paper":{"title":"Interlayer Five-Spin Polaron in Superconducting Bilayer Nickelates","license":"http://creativecommons.org/licenses/by/4.0/","headline":"Superconductivity in bilayer nickelates requires oxygen-stoichiometric regions that host an interlayer five-spin polaron ground state instead of spin density waves.","cross_cats":["cond-mat.supr-con"],"primary_cat":"cond-mat.str-el","authors_text":"Brian Moritz, Cheng-Tai Kuo, Christopher T. Parzyck, Chunjing Jia, Eder G. Lomeli, Eun Kyo Ko, Harold Y. Hwang, Heemin Lee, Jiarui Li, Jonathan Pelliciari, Jun-Sik Lee, Ronny Sutarto, Taehun Kim, Thomas P. Devereaux, Valentina Bisogni, Vivek Thampy, Wanli Yang, Wei-Sheng Lee, Yaoju Tarn, Yidi Liu, Yijun Yu, Zengqing Zhuo","submitted_at":"2026-05-04T17:59:37Z","abstract_excerpt":"The discovery of high-$T_c$ superconductivity in Ruddlesden-Popper nickelates has sparked substantial effort towards understanding unconventional electronic states beyond a traditional cuprate-like $d^9$ configurational ground state. An understanding of the interplay between magnetic ground states and multi-orbital physics is key for establishing a microscopic mechanism for superconductivity. In the bilayer nickelates, spin density wave (SDW) order is a prominent feature in the non-superconducting regime, yet its relation to superconducting pairing remains an open question. Here, we use resona"},"claims":{"count":4,"items":[{"kind":"strongest_claim","text":"Our results identify oxygen stoichiometry as a key parameter controlling interlayer coupling and thus the electronic structure of bilayer nickelates. In concert with theory, we propose that a ligand hole primarily resides at the inter-bilayer apical oxygen, forming a robust interlayer five-spin polaron state, which serves as the ground state for superconducting bilayer nickelates.","source":"verdict.strongest_claim","status":"machine_extracted","claim_id":"C1","attestation":"unclaimed"},{"kind":"weakest_assumption","text":"The assumption that the distinct electronic structures observed by Ni-L3 and O-K edge spectroscopy directly indicate a ligand hole at the inter-bilayer apical oxygen forming a five-spin polaron ground state, rather than other possible multi-orbital configurations or artifacts from phase segregation.","source":"verdict.weakest_assumption","status":"machine_extracted","claim_id":"C2","attestation":"unclaimed"},{"kind":"one_line_summary","text":"Superconductivity in bilayer nickelates occurs in SDW-free oxygen-stoichiometric regions, with an interlayer five-spin polaron proposed as the ground state.","source":"verdict.one_line_summary","status":"machine_extracted","claim_id":"C3","attestation":"unclaimed"},{"kind":"headline","text":"Superconductivity in bilayer nickelates requires oxygen-stoichiometric regions that host an interlayer five-spin polaron ground state instead of spin density waves.","source":"verdict.pith_extraction.headline","status":"machine_extracted","claim_id":"C4","attestation":"unclaimed"}],"snapshot_sha256":"a8c1bc1db18a60ee443277e72aad1cb70976d4cd9e91739d5ca9d5d32209e3c6"},"source":{"id":"2605.02891","kind":"arxiv","version":2},"verdict":{"id":"d59f84c6-3ae7-4502-bfee-149a5ee96e46","model_set":{"reader":"grok-4.3"},"created_at":"2026-05-08T18:02:47.956913Z","strongest_claim":"Our results identify oxygen stoichiometry as a key parameter controlling interlayer coupling and thus the electronic structure of bilayer nickelates. In concert with theory, we propose that a ligand hole primarily resides at the inter-bilayer apical oxygen, forming a robust interlayer five-spin polaron state, which serves as the ground state for superconducting bilayer nickelates.","one_line_summary":"Superconductivity in bilayer nickelates occurs in SDW-free oxygen-stoichiometric regions, with an interlayer five-spin polaron proposed as the ground state.","pipeline_version":"pith-pipeline@v0.9.0","weakest_assumption":"The assumption that the distinct electronic structures observed by Ni-L3 and O-K edge spectroscopy directly indicate a ligand hole at the inter-bilayer apical oxygen forming a five-spin polaron ground state, rather than other possible multi-orbital configurations or artifacts from phase segregation.","pith_extraction_headline":"Superconductivity in bilayer nickelates requires oxygen-stoichiometric regions that host an interlayer five-spin polaron ground state instead of spin density waves."},"integrity":{"clean":true,"summary":{"advisory":0,"critical":0,"by_detector":{},"informational":0},"endpoint":"/pith/2605.02891/integrity.json","findings":[],"available":true,"detectors_run":[{"name":"ai_meta_artifact","ran_at":"2026-05-20T14:40:02.793080Z","status":"completed","version":"1.0.0","findings_count":0},{"name":"doi_title_agreement","ran_at":"2026-05-20T02:01:22.364396Z","status":"completed","version":"1.0.0","findings_count":0},{"name":"doi_compliance","ran_at":"2026-05-19T15:51:57.103871Z","status":"completed","version":"1.0.0","findings_count":0}],"snapshot_sha256":"141ad59862f3c450d7f32844e5184ee0191b914c25dabdcc66a539b0ed84a9c3"},"references":{"count":0,"sample":[],"resolved_work":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57","internal_anchors":0},"formal_canon":{"evidence_count":3,"snapshot_sha256":"1509c4632235debbfab0fa668786c56150b15a86df7f7b22c8744f02d0f6e833"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"}