https://doi.org/10.1140/epjb/s10051-022-00447-1
Regular Article - Solid State and Materials
Reentrant superconductivity due to inter-band off-diagonal hopping in a two-band superconductivity model
1
Laboratory of SUPERCOMP, Physics Department, FACYT-UC, Valencia, Venezuela
2
Departamento de Matemática, CCNE, UFSM, CEP 97105-900, Santa Maria, RS, Brazil
3
Department of Physics, California State University, 92831, Fullerton, CA, USA
Received:
23
August
2022
Accepted:
21
October
2022
Published online:
3
November
2022
We present a possible phase diagram for the superconductivity state in a two-band scenario that includes contributions from the inter-orbital off-diagonal hopping term. Our model accounts for intra-band attractive electron–electron interactions that leads to the formation of superconducting Cooper pairs in each component band and for an inter-band attractive electron–electron interaction responsible for a single superconductive transition temperature 
in the model. Using a mean field approximation, we obtained an analytical equation for the superconducting critical temperature that includes contributions from a hybridization term due to the mixing of the two electron bands. For a numerical solution of this equation, we considered a band structure that reproduced as much as possible the situation in the Ba
K
Fe
As pnictide superconductor material. Our possible phase diagram vs. N is obtained assuming that Cooper pairs in both electron bands have either s-wave or 
-wave symmetry. The main result of our calculation is the existence of a complex phase diagram that at different inter-orbital hopping strengths can have one or two local maxima for the transition critical temperature . The electron concentration at which these maxima occur in the phase diagram can be tuned using the inter-orbital off-diagonal hopping term.
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© The Author(s), under exclusive licence to EDP Sciences, SIF and Springer-Verlag GmbH Germany, part of Springer Nature 2022. Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.
