相关论文: Paraconductivity of pseudogapped superconductors
It is shown that the famous Allen -- Dynes asymtotic limit for superconducting transition temperature in very strong coupling region $T_{c}>\frac{1}{2\pi}\sqrt{\lambda}\Omega_0$ (where $\lambda\gg 1$ - is Eliashberg - McMillan electron -…
The fluctuation conductivity $\sigma_{\rm s}$ in bulk superconductors with non s-wave pairing and with nonmagnetic disorder of strength $D$ is studied at low $T$ and within the Gaussian approximation. It is shown by assuming a quasi…
We first argue that the collective behaviour of the Cooper pairs created by thermal fluctuations well above the superconducting transition temperature, Tc, is dominated by the uncertainty principle which, in particular, leads to a…
We express the superconducting gap, $\Delta(T)$, in terms of thermodynamic functions in both $s$- and d-wave symmetries. Applying to Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$ and Y$_{0.8}$Ca$_{0.2}$Ba$_2$Cu$_3$O$_{7-\delta}$ we find that for all…
According to the Anderson theorem, the critical temperature T_c of a disordered superconductor is determined by the average density of states and does not change at the localization threshold. This statement is valid under assumption of a…
We study the effect of superconducting fluctuations on the conductivity of metals at arbitrary temperatures $T$ and impurity scattering rates $\tau^{-1}$. Using the standard diagrammatic technique but in the Keldysh representation, we…
We study temperature $T$ and frequency $\omega$ dependence of the in-plane fluctuation conductivity of a disordered superconducting film above the critical temperature. Our calculation is based on the nonlinear sigma model within the…
Contrary to the starting assumption of Grbi\'c et al. (Phys. Rev. B 83, 144508 (2011)), here we will first argue that a 16 T magnetic field is not enough to quench all superconducting fluctuations above Tc in YBa$_2$Cu$_3$O$_{7-\delta}$. We…
Temperature dependencies of excess conductivity, Sigma', have been studied in detail for three FeSe_{0.94} textured polycrystalline samples prepared by partial melting and solid state reaction. It was revealed that both Sigma' and its…
There exists a wide temperature region $({\rm Gi}T<T-T_c<T\sqrt{{\rm Gi}})$, where the influence of fluctuations on the thermodynamic properties of superconductors can be taken into account in the linear (Gaussian) approximation, while…
We investigate validity of Anderson's theorem (AT) for disordered s-wave superconductors in a negative U Hubbard model with random on-site energies, $\epsilon_{i}$. The superconducting critical temperature, $T_{c}$, is calculated in the…
A detailed theoretical analysis of the Gaussian fluctuations of the order parameter in layered superconductors is performed within the Ginzburg-Landau (GL) theory. The available results for the Gaussian fluctuations are systematized and a…
The effect of fluctuations on the transport and thermodynamic properties of two-dimensional superconductors in a magnetic field is studied at low temperature. The fluctuation conductivity is calculated in the framework of the perturbation…
We study the superconducting instability in systems with long but finite ranged, attractive, pairing interactions. We show that such long-ranged superconductors exhibit a new class of fluctuations in which the internal structure of the…
Abrikosov-Gor'kov (AG) theory, the foundation for understanding pair-breaking effects in conventional superconductors, is inadequate when there is an excitation gap (pseudogap) present at the onset of superconductivity. In this paper we…
The influence of the hydrostatic pressure P up to 0.95 GPa on the excess conductivity and the pseudogap {\Delta}*(T) in optimally doped YBCO single crystals (T_c = 91.1K at ambient pressure) is investigated by electrical resistivity…
We review recent work on a continuum, classical theory of thermal fluctuations in two dimensional superconductors. A functional integral over a Ginzburg-Landau free energy describes the amplitude and phase fluctuations responsible for the…
Large pulsed magnetic fields up to 60 Tesla are used to suppress the contribution of superconducting fluctuations (SCF) to the ab-plane conductivity above Tc in a series of YBa2Cu3O(6+x). These experiments allow us to determine the field…
Current-voltage characteristics and dynamic conductance of the superconductor - constriction - superconductor junctions in GdO(F)FeAs polycrystalline samples with critical temperatures Tc^local = 46 - 53 K were investigated. Two…
The first-order superconducting fluctuation corrections to the thermal conductivity of a granular metal are calculated. A suppression of thermal conductivity proportional to $T_c/(T-T_c)$ is observed in a region not too close to the…