Specific heats and thermodynamic critical fields in Zn-doped YBa2Cu3O7 − x according to an induced-pairing model

✍ Scribed by D.M. Eagles

• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 709 KB
• Volume: 211
• Category: Article
• ISSN: 0921-4534
• DOI: 10.1016/0921-4534(93)90138-g

✦ Synopsis

Electronic specific heats and thermodynamic critical fields are calculated in a mean-field version of an induced-pairing model for superconductivity, and compared with results of Loram el al. on YBa2(Cu~ _rZny)30~_x. This model involves induction of pairing of holes in a wide band by strongly bound electron-like pairs. It is assumed that the planar hole concentration for no Zn addition is close to, but slightly higher than, that for the maximum To, and that it increases by 0.015 per planar Cu ion for each increase ofy by 0.01. Parameters of the model are taken to be the same as in a previous publication in which energy gaps were discussed, except that an effective hybridization parameter is adjusted for each Zn concentration to give agreement with the observed T,. Results are presented for y=0.0, 0.01 and 0.03. The agreement with experiment is good for thermodynamic critical fields, and is fair for specific heats. For specimens with larger y, with relatively low To's, it is argued that the model should be supplemented to include effects ofa BCS-type interaction amongst the wide-band carriers.