{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"83ec4143594830a929b53db00f85b216bbc62d59c0b9b37a527686031a0f51df","created":"2026-10-03T07:17:59Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["1f1cdf9130b4f02912f9ac1aadbd10c2f51d4d3acbacda170fcbc080c3235748","5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"637c171e73aa67c1f01f82ddb7d263127fa5cefc868e4fa80786ea9a8f5b3c87","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"yes-no","assisted_by":[],"external_id":"cm.cuprates.charge-transfer-tc","kind":"well-posed","literature_status":"partially-resolved","n":"1","parents":[{"note":"","parent_revision":"1f1cdf9130b4f02912f9ac1aadbd10c2f51d4d3acbacda170fcbc080c3235748","relation":"special_case"}],"plain":"The energy needed to move an electron from oxygen to copper, the charge-transfer gap, differs between cuprate families; superexchange theories predict that a smaller gap gives stronger pairing and a higher transition temperature.","posed_since":"","precise":"For hole-doped cuprates at optimal doping, test whether T_c,max and the zero-temperature pair density decrease monotonically with the charge-transfer energy $\\Delta_{\\mathrm{CT}}$ (equivalently increase with $J\\sim t_{\\mathrm{pd}}^4/\\Delta_{\\mathrm{CT}}^3$), as superexchange pairing in the three-band Emery model predicts. An answer is a cross-family data set ($\\Delta_{\\mathrm{CT}}$ from optics or tunneling, T_c,max, superfluid density) with a quantitative fit to model predictions, or a counterexample family.","problem_ref":null,"references":"","settled_by":"Measurement of $\\Delta_{\\mathrm{CT}}$ and the pair or superfluid density in at least five cuprate families, compared with three-band model calculations of $T_{c}$ versus $\\Delta_{\\mathrm{CT}}$.","status_note":"Scanning tunneling spectroscopy on Bi2Sr2CaCu2O8+x (2022) found that the local pair density anticorrelates with the local charge-transfer gap; a cross-family quantitative test is incomplete.","title":"Does the charge-transfer gap set the maximum $T_{c}$ across cuprate families","topic_ref":"33286b282c1fb96cb91bff4da60a136df7a46ad812b8b7d94aa4475e741e6e76"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"52bb616da835c6b5ed2c7b2995fd1bb72e78ca25ae52034db5d55c2a3a338655","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"c4a24fd96a9ca1af8fdee63b007d6de40f4f29f854ad54225b3fbfdc39237407","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"leraiTzzRqNZrrweljpYzB80DDzQzCjZ4mvG5f--AmJaHEyJQx0tZwWgnzZW4cJwr6Rbnd-NWFHBZXcWveElAQ"},"schema":"pubphys.envelope/1"},"record_hash":"52bb616da835c6b5ed2c7b2995fd1bb72e78ca25ae52034db5d55c2a3a338655","leaf_index":936}