{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"ce5423d5b39636e01d1ef8465abcbea15da742a5a9c21d9f3c22aa8d85c4c838","created":"2026-10-03T07:18:01Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"19a153232746266b31146efc025a69f53bdbebedfac9cef9365c29bfb43ac9e2","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"classification","assisted_by":[],"external_id":"cm.sit-anomalous-metal.pairing-or-phase-route","kind":"well-posed","literature_status":"open","n":"1","parents":[],"plain":"Disorder can end superconductivity in two ways: by breaking the electron pairs, or by leaving the pairs intact but stopping them from moving together in step. Some films, such as amorphous indium oxide and titanium nitride, keep a pairing gap into the insulator, while in others the gap seems to close together with the transition temperature, and what selects the route is not known.","posed_since":"","precise":"Near the disorder-tuned 2D superconductor-insulator transition, the fermionic route (Coulomb-enhanced suppression of the pairing amplitude, Finkel'stein) has the gap $\\Delta\\to 0$ together with $T_c$, while the bosonic route keeps a finite $\\Delta$ and a pseudogap above $T_c$, with $T_c\\to 0$ from phase fluctuations or localization of preformed pairs (Sacepe et al., Nature Physics 2011, in InOx). Identify the material parameter that selects the route (for example $k_F\\ell$, the ratio of Coulomb to pairing strength, or the Debye energy relative to the level spacing in a localization volume) and give a criterion that predicts the route for a given film.","problem_ref":null,"references":"","settled_by":"Tunneling measurements of $\\Delta(T)$ and $T_c$ across disorder series in several material families, matched to a theory whose criterion predicts each family's route in advance.","status_note":"A 2020 review describes both routes and granular behavior without a predictive criterion (Sacepe, Feigel'man and Klapwijk, Nature Physics 16, 734, 2020); a first-order disorder-driven transition was reported in InOx in 2025 (Charpentier et al., Nature Physics 21, 104).","title":"What decides whether disorder destroys pairing or only phase coherence?","topic_ref":"4ea1b2157b1b787fb021cb15b1d29d6f209084de7dc217220a6bd4b6bab225a2"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"ac840874faa4db0c8e5d8fc62428073efb15e3c4381a2061b8423107f64f9049","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"d09c017f28af3d5ae3bd3357b6c7e0efbc7bed581a781615d26eee16eb07f2fe","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"wBolbbLVofczIB51tuI1zeP4aWSN3WZ-Geb1zqMO7i_xxmqcdyateHe5ZaWByEUKMwo-7StjqjFPqADcYLSZDQ"},"schema":"pubphys.envelope/1"},"record_hash":"ac840874faa4db0c8e5d8fc62428073efb15e3c4381a2061b8423107f64f9049","leaf_index":1162}