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Isotropic Bipolaron-Fermion Exchange Theory and Unconventional Pairing in Cuprate Superconductors

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Bru, Jean-Bernard [1, 2, 3] ; de Siqueira Pedra, Walter [4] ; Delgado de Pasquale, Antonio [4]
Número total de Autores: 3
Afiliação do(s) autor(es):
[1] Basque Fdn Sci, Ikerbasque, Bilbao 48011 - Spain
[2] BCAM, Mazarredo 14, Bilbao 48009 - Spain
[3] Univ Basque Country, Fac Ciencias & Tecnol, Dept Matemat, Apartado 644, E-48080 Bilbao - Spain
[4] Univ Sao Paulo, Inst Fis, Rua Matao 187, BR-05508090 Sao Paulo - Brazil
Número total de Afiliações: 4
Tipo de documento: Artigo Científico
Fonte: Annalen der Physik; v. 531, n. 1 JAN 2019.
Citações Web of Science: 0

The appearance of unconventional pairing in superconducting cuprates is examined from a microscopic model, taking into account important properties of hole-doped copper oxides. An exchange interaction between fermions and dominantly inter-site bipolarons is considered to be the mechanism which leads to the pairing. Its momentum dependency is connected to the well-established fermion-phonon anomalies in cuprate superconductors. Since charge carriers in these materials are strongly correlated, a screened Coulomb repulsion is added to this exchange term. Any ad hoc assumptions like anisotropy are avoided, but a microscopic explanation of unconventional pairing for coupling strengths that are in accordance with experimental facts is provided. One important outcome is a mathematically rigorous elucidation of the role of Coulomb repulsion in unconventional pairing, which is shown to be concomitant with a strong depletion of superconducting pairs. The theory, applied to the special case of LaSr 214, predicts at optimal doping i) a coherence length of 21 angstrom, which is the same as that obtained from the Ginzburg-Landau critical magnetic field measured for this material, and ii) d-wave pair formation in the pseudogap regime, that is, at temperatures much higher than the superconducting transition temperature. (AU)

Processo FAPESP: 16/02503-8 - Comportamento macroscópico de sistemas de férmions não relativísticos interagentes
Beneficiário:Walter Alberto de Siqueira Pedra
Linha de fomento: Bolsas no Exterior - Pesquisa
Processo FAPESP: 17/22340-9 - Métodos construtivos para férmions interagentes com aplicações a teoria microscópica da condutividade e supercondutividade
Beneficiário:Walter Alberto de Siqueira Pedra
Linha de fomento: Auxílio à Pesquisa - Pesquisador Visitante - Internacional