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1

Fluctuation conductivity in two-band superconductor SmFeAsO0.8F0.2

Askerzade I. N., Tagiyeva-Askerbeyli R. T.

Materials Science Poland

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2015

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Vol. 33, No. 3

644--648

EN

In this study we have calculated the fluctuation conductivity near critical temperature of SmFeAsO0.8F0.2 superconductor using two-band Ginzburg-Landau theory. It was illustrated that in the absence of external magnetic field, the two-band model reduced to a single effective band theory with modified temperature dependences. The calculations revealed three-dimensional character of fluctuations of conductivity in the new Fe-based superconductor SmFeAsO0.8F0.2. It has been shown that such a model is in good agreement with experimental data for this compound.

2

Probability densities of superconductors

Gamalath K. A. I. L. W., Udeni G. D. K. N.

International Letters of Chemistry, Physics and Astronomy

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2015

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Vol. 41

31--44

EN

The energy, current density and momentum probability densities of superconductors were studied from London, Ginzburg-Landau and BSC theories by treating cooper pair as a particle moving in a magnetic field through analytical and numerical techniques. The London and GL solution were exactly the same at the classical limit for NbN. Considering a Cooper pair as a complete classical particle, the momentum probability density was derived by using the Maxwell velocity distribution and the quantum mechanical momentum probability density was derived by using the radial wave function of the cooper pairs for Zn. The quantum mechanical and classical momentum probability densities overlap at zero momentum.

3

Specific heat jump of two-band superconductor KFe2As2 using Ginzburg-Landau theory

Askerzade I N

Materials Science Poland

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2014

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Vol. 32, No. 3

465--469

EN

In this study specific heat jump using two-gap Ginzburg-Landau (GL) theory has been calculated. In contrast to the previous approaches, we have taken into account intergradient order parameters interaction in the GL free energy functional. The thermodynamic magnetic field revealed nonlinear temperature dependence due to interband interaction between order parameters and their gradients. The calculations showed that the specific heat jump in two-order parameter superconductors was smaller than that of single-order parameter superconductors. It has been shown that such a model is in good agreement with experimental data for KFe2As2 superconductors.

4

Extended Ginzburg-Landau theory of magnetically active anisotropic superconductors

Rogula D.

Journal of Technical Physics

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2004

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Vol. 45, no 3

243-251

EN

A formulation of thermodynamical theory of magnetically active, anisotropic materials admitting coexistence of the superconductivity and magnetic order is proposed. The theory is based on the Ginzburg-Landau approach extended to multi-component order parameters and the states of thermodynamic quasi-equilibrium far from the superconducting phase transition. The field equations are derived under assumption of the U(1) gauge invariance. The questions of exact anisotropic similarity transformations as well as approximate anisotropic scaling are discussed.

5

Inhomogeneous superconductivity and vortices in the stripe states

Lenkowska-Czerwińska T.

Journal of Technical Physics

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2002

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Vol. 43, no 3

335-341

EN

Spatially inhomogeneous features in the spin and charge structures have been indicated in the number of experiments on high temperature materials e.g. La2-xSrxCuO4. The simple realization of this state is striped domain wall where charges form a nanoscale linear pattern in an antiferromagnetically ordered isolator. These represent a nanoscale distribution of charge and spin that is believed to be commensurably locked by the tilt distortions of the lattice. The phenomenological model of charge and spin inhomogeneities in the stripe phase of superconducting cuprates on the ground of Ginzburg-Landau theory is proposed. The corresponding free energy for the coupled charge and spin-density wave, and superconducting order parameters is constructed. The phase diagram for inhomogeneous superconducting state is discussed. The effective coherence length and the penetration depth in the London limit are introduced. The critical magnetic fields and the energy of the isolated vortex line are obtained.