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Two-band superconductors : Extended Ginzburg-Landau formalism by a systematic expansion in small deviation from the critical temperature

Title data

Vagov, Alexei ; Shanenko, A. A. ; Milošević, M. V. ; Axt, Vollrath M. ; Peeters, F. M.:
Two-band superconductors : Extended Ginzburg-Landau formalism by a systematic expansion in small deviation from the critical temperature.
In: Physical Review B. Vol. 86 (2012) Issue 14 . - Art.Nr. 144514, 13 S..
ISSN 0163-1829
DOI: https://doi.org/10.1103/PhysRevB.86.144514

Project information

Project financing: Supported by the Flemish Science Foundation (FWO-Vl)

Abstract in another language

We derive the extended Ginzburg-Landau (GL) formalism for a clean s-wave two-band superconductor by employing a systematic expansion of the free-energy functional and the corresponding matrix gap equation in powers of the small deviation from the critical temperature τ=1−T/Tc. The two lowest orders of this expansion produce the equation for Tc and the standard GL theory. It is shown that in agreement with previous studies, this two-band GL theory maps onto the single-band GL model and thus fails to describe the difference in the spatial profiles of the two-band condensates. We prove that this difference appears already in the leading correction to the standard GL theory, which constitutes the extended GL formalism. We derive linear differential equations that determine the leading corrections to the band order parameters and magnetic field, discuss the validity of these equations, and consider examples of an important interplay between the band condensates. Finally, we present numerical results for the thermodynamic critical magnetic field and temperature-dependent band gaps for recent materials of interest, which are in very good agreement with those obtained from the full BCS approach in a wide temperature range. To this end, we emphasize the advantages of our extended GL theory in comparison with the often used two-component GL-like model based on an unreconstructed two-band generalization of the Gor'kov derivation

Further data

Item Type: Article in a journal
Refereed: Yes
Keywords: superconductivity; two-band superconductor; BCS; extended Landau Ginzburg theory
Institutions of the University: Faculties > Faculty of Mathematics, Physics und Computer Science > Department of Physics
Faculties > Faculty of Mathematics, Physics und Computer Science > Department of Physics > Chair Theoretical Physics III > Chair Theoretical Physics III - Univ.-Prof. Dr. Martin Axt
Faculties
Faculties > Faculty of Mathematics, Physics und Computer Science
Faculties > Faculty of Mathematics, Physics und Computer Science > Department of Physics > Chair Theoretical Physics III
Result of work at the UBT: Yes
DDC Subjects: 500 Science > 530 Physics
Date Deposited: 03 Nov 2017 06:42
Last Modified: 03 Nov 2017 06:42
URI: https://eref.uni-bayreuth.de/id/eprint/40246