Electronic specific heat of two-band layered superconductors: Analysis within the generalized two-band<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>α</mml:mi></mml:math>model

Maksimov, Evgenii G.; Karakozov, A. E.; Gorshunov, B.; Жукова, Е. С.; Ponomarev, Ya. G.; Dressel, Martin

doi:10.1103/physrevb.84.174504

Cited by 18 publications

(17 citation statements)

References 19 publications

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“…Obviously the heat capacity in the normal phase is not dependent on J. Similar behavior has been described theoretically using α model e.g., in MgB 2 [68][69][70], where interactions are described by the electronphonon coupling. Figure 6.…”

Section: Specific Heatsupporting

confidence: 69%

Effects of Pair-Hopping Coupling on Properties of Multi-Band Iron-Based Superconductors

2020

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A variety of superconducting materials exhibit multi-band behavior in a form of multicomponent Fermi surfaces. By using a two-band model with a pair hopping, we explain how the interband coupling affects the physical properties of multi-band superconductors. We determine the temperature dependence of the superconducting gap and the specific heat, which strongly diverge from the BCS-type behavior. The anisotropic gap for the system with the mixed gap symmetry is found. Additionally, the spectral function and density of states are significantly modified by the inter-orbital interactions. The results obtained for different symmetries of the order parameter are in a good agreement with the experimental findings for the iron-based superconductors and other multi-band systems.

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Section: Specific Heatsupporting

confidence: 69%

Effects of Pair-Hopping Coupling on Properties of Multi-Band Iron-Based Superconductors

2020

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“…An advanced multiband Eliashberg analysis along these lines is necessary to reconsider/check the strong coupling results mentioned above. A weak-coupling interband regime within twoand three-band descriptions has also been found for Codoped Ba-122 [63,103], based on specific heat and optical data. These works found a non-BCS shape of the T -dependent small gap functions, which affected the behavior of the penetration depth, in contrast to a BCS-like shape expected for a dominant interband coupling.…”

Section: Figurementioning

confidence: 77%

“…In doing so, one usually finds (see e.g., Ref. that one of the Drude peaks is quite broad compared to the other. This also happens in the two special cases under consideration Ca‐122 and K‐122 .…”

Section: Introductionmentioning

confidence: 99%

Constraints on the total coupling strengthto bosons in the iron based superconductors

Drechsler

Johnston

Grinenko

et al. 2017

Phys. Status Solidi B

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Despite the fact that the Fe-based superconductors (FeSCs) were discovered nearly ten years ago, the community is still devoting a tremendous effort towards elucidating their relevant microscopic pairing mechanism(s) and interactions. At present, there is still no consistent interpretation of their normal state properties, where the strength of the electron-electron interaction and the role of correlation effects are under debate. Here, we examine several common materials and illustrate various problems and concepts that are generic for all FeSCs. Based on empirical observations and qualitative insight from density functional theory, we show that the superconducting and low-energy thermodynamic properties of the FeSCs can be described semi-quantitively within multiband Eliashberg theory. We account for an important high-energy mass renormalization phenomenologically, and in agreement with constraints provided by thermodynamic, optical, and angle-resolved photoemission data. When seen in this way, all FeSCs with T c < 40 K studied so far are found to belong to an intermediate coupling regime. This finding is in contrast to the strong coupling scenarios proposed in the early period of the FeSC history. We also discuss several related issues, including the role of band shifts as measured by the positions of van Hove singularities, and the nature of a recently suggested quantum critical point in the strongly hole-doped systems AFe 2 As 2 (A = K, Rb, Cs). Using high-precision full relativistic GGA-band structure calculations, we arrive at a somewhat milder mass renormalization in comparison with previous studies. From the calculated mass anisotropies of all Fermi surface sheets, only the ε-pocket near the corner of the BZ is compatible with the experimentally observed anisotropy of the upper critical field, pointing to its dominant role in the superconductivity of these three compounds.

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“…This is somewhat surprising for two reasons. First, the curve has not been refined in any way, and second, this is a simple superposition of two single-band BCS models and not a more sophisticated two-band model of superconductivity that considers both intraband as well as interband pairing [64][65][66]. On the other hand, since this approach appears to work rather well, we speculate that the large difference in the scattering rates in the two bands allows for this simpler interpretation.…”

Section: Multiband Superconductormentioning

confidence: 99%

FeTe0.55Se0.45: A multiband superconductor in the clean and dirty limit

et al. 2015

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The detailed optical properties of the multiband iron-chalcogenide superconductor FeTe0.55Se0.45 have been reexamined for a large number of temperatures above and below the critical temperature Tc = 14 K for light polarized in the a-b planes. Instead of the simple Drude model that assumes a single band, above Tc the normal-state optical properties are best described by the two-Drude model that considers two separate electronic subsystems; we observe a weak response (ωp,D;1 3000 cm −1 ) where the scattering rate has a strong temperature dependence (1/τD,1 32 cm −1 for T Tc), and a strong response (ωp,D;2 14 500 cm −1 ) with a large scattering rate (1/τD,2 1720 cm −1 ) that is essentially temperature independent. The multiband nature of this material precludes the use of the popular generalized-Drude approach commonly applied to single-band materials, implying that any structure observed in the frequency dependent scattering rate 1/τ (ω) is spurious and it cannot be used as the foundation for optical inversion techniques to determine an electron-boson spectral function α 2 F (ω). Below Tc the optical conductivity is best described using two superconducting optical gaps of 2∆1 45 and 2∆2 90 cm −1 applied to the strong and weak responses, respectively. The scattering rates for these two bands are vastly different at low temperature, placing this material simultaneously in both clean and dirty limit. Interestingly, this material falls on the universal scaling line initially observed for the cuprate superconductors.

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Electronic specific heat of two-band layered superconductors: Analysis within the generalized two-bandαmodel

Cited by 18 publications

References 19 publications

Effects of Pair-Hopping Coupling on Properties of Multi-Band Iron-Based Superconductors

Effects of Pair-Hopping Coupling on Properties of Multi-Band Iron-Based Superconductors

Constraints on the total coupling strengthto bosons in the iron based superconductors

FeTe0.55Se0.45: A multiband superconductor in the clean and dirty limit

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