{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"d2b179896eb8aaeff5fd865cc45cc67bb0809d23e4792815d0ba482d2f25e666","created":"2026-10-03T07:17:59Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"bff4002e6b8d1204ed230d716b27ad5fe5f76422b7e739fab40860407845da87","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"classification","assisted_by":[],"external_id":"cm.cuprate-pseudogap.origin","kind":"phenomenon","literature_status":"contested","n":"1","parents":[],"plain":"Above the superconducting temperature, underdoped cuprates lose many low-energy electron states, a partial gap called the pseudogap; it is unclear whether this is a separate phase of matter, pairs without long-range order, or a gradual crossover.","posed_since":"1989","precise":"Identify the state below $T*(p)$ in hole-doped cuprates for $p < p* \\sim 0.19$: a broken-symmetry phase (intra-unit-cell loop currents, nematic order, pair density wave, fluctuating antiferromagnet), a fractionalized metal with small Fermi pockets ($\\mathrm{FL}*$), or a crossover. An answer specifies the order parameter or topological character and accounts for the Fermi arcs, the Knight-shift suppression, and the drop of Hall carrier density from $1+p$ to p near $p*$.","problem_ref":null,"references":"","settled_by":"A symmetry-resolved or thermodynamic measurement establishing a phase transition at $T*$, plus a theory that reproduces the carrier-density change at $p*$ and the arc spectrum.","status_note":"","title":"What is the pseudogap state of underdoped cuprates","topic_ref":"0b1624cb419c381bddad004c2bf5315f0b67a5717967d1ceb30488890c34b90a"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"946651e45560029973e85184727aeb29e0c77ad6e6c7e6779b82d81a1358b32c","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"8ad5119fd9c5806e7c14a7deb919078f76a5b665b8f4d0c2c15ac0dac8c7646f","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"p95CoooOAF7mf3aUcr3SH_3w7zU8F-EnxFnY8PaOkiLsHSgXZaEdNpCLj7lV02TeWY2IizPwlRoD5MOzJhcpBA"},"schema":"pubphys.envelope/1"},"record_hash":"946651e45560029973e85184727aeb29e0c77ad6e6c7e6779b82d81a1358b32c","leaf_index":930}