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Simultaneous Action of Intra- and Interband Pair Channels in Multiband Superconductivity

  • Nikolai Kristoffel
  • Pavel Rubin
Original Paper

Abstract

Interband superconductivity channels with pairs formed from the same (a) and different bands (b) are compared in common action. A simple mean-field multiband model is inspected. There are three order parameters Δ a , Δ a d and \({\Delta }_{b} \left ({\Delta }_{b1}^{2}={\Delta }_{b2}^{2} \right )\). Complicated quasiparticle energies induced by interactions of strengths W a and W b follow. The calculated operator averages lead to a coupled nonlinear system for the gap-type parameters. Illustrative calculations of them vs temperature have been made. Overlapping dispersive bands intersected by the chemical potential have been used. A novel result is that at a fixed parameter set the system of basic equations has two independent solutions. The free energy is of a complicated structure under the action of both channels. There are stable and metastable states. The W a and W b channels compete in simultaneous functioning. The phenomenon of the effective logout of one of the channels can be traced. Starting by the temperature where Δ i reached zero, the solutions induced by W j behaving as W i were zero and define T c i . The pairs Δ a and Δ a d have the same vanishing temperature. The general results are very sensible to |W b | inclusive to critial behaviour. Reduced |W b | stimulates the formation of closed “bubbles” built up by Δ a , Δ b and Δ a d belonging to parallel solutions. The corresponding metastable state vanishes when the bubble closes.

Keywords

Multiband superconductivity Intraband pairs Interband pairs 

Notes

Funding

This work was partially supported by the European Union through the European Regional Development Fund.

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Copyright information

© Springer Science+Business Media New York 2015

Authors and Affiliations

  1. 1.Institute of PhysicsUniversity of TartuTartuEstonia

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