{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"e58f53e321ca3a3682b6f1a7ee6a596ea43bf4e923ec47878f1d7752fdbec907","created":"2026-10-15T23:43:22Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["10792a105c208d2b2ed78b98e135cae2eaa7b263fcc6b163094b09ea866a72ca","ce59fb6cd812fc05906d0c60a71c75ea22bc686bcf38e7c3ef7010834d98ee7b"],"salt":"f564728d93a1f789efaff20f98a7da68a47ee3053540944960cb6a2111f22cd4","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"yes-no","assisted_by":[],"external_id":"cm.iron-based.s-pm-sign-change","kind":"well-posed","literature_status":"partially-resolved","n":"2","parents":[],"plain":"The leading theory says the pairing amplitude has opposite sign on different pockets of the Fermi surface ($s\\pm$ pairing); several experiments support it but a direct sign measurement is lacking.","posed_since":"2008","precise":"In bulk iron pnictides with both hole pockets at $\\Gamma$ and electron pockets at $M$ (for example Ba1-xKxFe2As2, LiFeAs), establish by a phase-sensitive probe whether the gap changes sign between them ($s\\pm$) or not ($s++$). An answer is a measurement in which the sign enters directly, such as a Josephson interferometer or phase-referenced quasiparticle interference with known impurity potentials.","problem_ref":"10792a105c208d2b2ed78b98e135cae2eaa7b263fcc6b163094b09ea866a72ca","references":"","settled_by":"A phase-sensitive interference or Josephson experiment with an unambiguous sign signature reproduced in two materials.","status_note":"Neutron spin resonance and phase-referenced quasiparticle interference support $s\\pm$; some impurity-scattering results were argued to favor $s++$.","title":"Does the gap change sign between hole and electron pockets?","topic_ref":null},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"7bc69bc05dab276313d591c28158aacd4b60dd51c0e87bcae78d31cf0f2c4852","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"c8ec1376567e05bf896e42874d4da884fd4c77a722ae8bf3a376b5f9f1be075d","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"h2VYnMXhsc0Wq7SN-OY3fIG7XvwmXMfnuHT34rvojwLccN6Zd87-yovSSIBq_L6_cWE5Xph17Vytbwop29BpBg"},"schema":"pubphys.envelope/1"},"record_hash":"7bc69bc05dab276313d591c28158aacd4b60dd51c0e87bcae78d31cf0f2c4852","leaf_index":2884}