Extended Uniform Ginzburg-Landau Theory for Novel Multiband Superconductors

Abstract

The recently discovered multiband superconductors have created a new class of novel superconductors. In these materials multiple superconducting gaps arise due to the formation of Cooper pairs on different sheets of the Fermi surfaces. An important feature of these superconductors is the interband couplings, which not only change the individual gap properties, but also create new collective modes. Here we investigate the effect of the interband couplings in the Ginzburg-Landau theory. We produce a general ${\tau }^{(2n+1)/2}$ expansion ($\tau =1-T/T_c$) and show that this expansion has unexpected behaviour for $n\ge 2$. This point emphasises the weaker validity of the GL theory for lower temperatures and gives credence to the existence of hidden criticality near the critical temperature of the uncoupled subdominant band.

10 pages, 4 figures

References in corpus (4)

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• Two-band superconductors: Hidden criticality deep in the superconducting state
• Ginzburg-Landau theory for multiband superconductors: microscopic derivation
• Multi-gap superconductivity and Shubnikov-de Haas oscillations in single crystals of the layered boride OsB_2