Reentrant superconductivity due to inter-band off-diagonal hopping in a two-band superconductivity model

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 p...

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Bibliographic Details
Published in:The European physical journal. B, Condensed matter physics Condensed matter physics, 2022-11, Vol.95 (11), Article 179
Main Authors: Núñez, J. J. Rodríguez, Schmidt, A. A., Tifrea, I.
Format: Article
Language:English
Subjects:
Analysis
Complex Systems
Condensed Matter Physics
Cooper pairs
Electron-electron interactions
Fluid- and Aerodynamics
Group 5A compounds
Phase diagrams
Physics
Physics and Astronomy
Regular Article - Solid State and Materials
Solid State Physics
Superconductivity
Superconductors
Transition temperature
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Summary: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 T c 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 1 - x K x Fe 2 As 2 pnictide superconductor material. Our possible phase diagram T c vs. N is obtained assuming that Cooper pairs in both electron bands have either s -wave or s ± -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 T c . The electron concentration at which these maxima occur in the phase diagram can be tuned using the inter-orbital off-diagonal hopping term. Graphic abstract
ISSN:1434-6028
1434-6036
DOI:10.1140/epjb/s10051-022-00447-1