Fluctuations in two-band superconductors in a strong magnetic field

Abstract

We consider the behaviour of the fluctuating specific heat and conductivity in the vicinity of the upper critical field line for a two-band superconductor. Multiple-band effects are pronounced when the bands have very different coherence lengths. The transition to superconductive state is mainly determined by the properties of the rigid condensate of the "strong" band, while the "weak" band with a large coherence length of the Cooper pairs causes the nonlocality in fluctuation behaviour and break down of the simple Ginzburg-Landau picture. As expected, the multiple-band electronic structure does not change the functional forms of dominating divergencies of the fluctuating corrections when the magnetic field approaches the upper critical field. The temperature dependence of the coefficients, however, is modified. The large in-plane coherence length sets the field scale at which the upper critical field has upward curvature. The amplitude of fluctuations and fluctuation width enhances at this field scale due to reduction of the effective z-axis coherence length. We also observe that the apparent transport transition displaces to lower temperatures with respect to the thermodynamic transition. Even though this effect exists already in a single-band case at sufficiently high fields, it may be strongly enhanced in multiband materials.

arXiv comment15 pages, 1 figure, submitted to the Superconductor Science and Technology, special issue on Multicomponent Superconductivity

References in corpus (38)

• The Puzzle of High Temperature Superconductivity in Layered Iron Pnictides and Chalcogenides
• Superconductivity in Iron Compounds
• High-temperature superconductivity in iron-based materials
• Gap symmetry and structure of Fe-based superconductors
• Enhancement of the upper critical field by nonmagnetic impurities in dirty two-gap superconductors
• The Nernst effect in high-$T_c$ superconductors
• Upper critical fields and thermally-activated transport of Nd(O_0.7F_0.3)FeAs single crystal
• The Ginzburg-Landau Theory of Type II superconductors in magnetic field
• Superfluid density and specific heat within self-consistent scheme for two-band superconductor
• Properties of the superconducting state in a two-band model
• Upper critical field in dirty two-band superconductors: breakdown of the anisotropic Ginzburg-Landau theory
• Observation of the Nernst signal generated by fluctuating Cooper pairs
• Psuedo-isotropic upper critical field in cobalt-doped SrFe2As2 epitaxial films
• Disorder and Quantum Fluctuations in Superconducting Films in Strong Magnetic Fields
• Two-gap and paramagnetic pair-breaking effects on upper critical field of SmFeAsO${}_{0.85}$ and SmFeAsO${}_{0.8}$F${}_{0.2}$ single crystals
• Decrease of upper critical field with underdoping in cuprate superconductors
• Superconducting fluctuations at low temperature
• Thermodynamic phase diagram of Fe(Se${}_{0.5}$Te${}_{0.5}$) single crystals up to 28 Tesla
• Giant Nernst Effect due to Fluctuating Cooper Pairs in Superconductors
• Superconducting phase transitions in ultrathin TiN films
• Multiband effects on beta-FeSe single crystals
• Why magnesium diboride is not described by anisotropic Ginzburg-Landau theory
• Phase textures induced by dc current pairbreaking in multilayer structures and two-gap superconductors
• Different length-scales for order parameters in two-gap superconductors: the extended Ginzburg-Landau theory
• Fluctuoscopy of Disordered Two-Dimensional Superconductors
• Multiorbital effects on the transport and the superconducting fluctuations in LiFeAs
• Fluctuations of the superconducting order parameter as an origin of the Nernst effect
• Microscopic analysis of the superconducting quantum critical point: Finite temperature crossovers in transport near a pair-breaking quantum phase transition
• Fluctuation conductivity of thin films and nanowires near a parallel-field-tuned superconducting quantum phase transition
• Theory of fluctuations in a two-band superconductor
• Anisotropic fluctuations and quasiparticle excitations in FeSe_0.5Te_0.5
• Fluctuation conductivity in disordered superconducting films
• Quantum Fluctuations and Dynamic Clustering of Fluctuating Cooper Pairs
• Superconducting Diamagnetic Fluctuations in MgB2
• Paraconductivity of K-doped SrFe2As2 superconductor
• Fluctuation Study of the Specific Heat of MgB2
• Two-bands effect on the superconducting fluctuating diamagnetism in MgB&#8322
• Fluctuation conductivity of disordered superconductors in magnetic fields

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• Large increase of the anisotropy factor in the overdoped region of Ba(Fe${}_{1-x}$Ni${}_x$)${}_2$As${}_2$ as probed by fluctuation spectroscopy