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Solutions for the higher-grade hybrid model of layered superconductors

Sztyren M.

Journal of Technical Physics

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2006

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Vol. 47, no 3

149-157

EN

A class of basic solutions for a model of layered superconductors is constructed. The considerations are based on the higher-grade hybrid model, constructed in the previous paper. In particular, for any range K of the Josephson interlayer couplings, we determine the spectrum of excited states with respect to all types of ground states calculated there for an infinite uniform superconductor. We discuss also solutions for a finite number of layers with periodic boundary conditions. In this way, instances of the amplitude-modulated solutions for the infinite stack of layers are found.

2

Long-range Josephson couplings in superconducting systems

Rogula D., Sztyren M.

Journal of Technical Physics

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2006

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Vol. 47, no 2

73-81

EN

Microstructured superconductors with long-range Josephson couplings are considered. The higher-grade hybrid model of layered superconductors is generalized to other microstructural geometries. The effects of broken symmetry with respect to the time reversal are described with the aid of complex Josephson coupling constants. This formalism is applied to the discussion of stability of the uniform, alternating, and phase-modulated states of a layered superconductor.

3

Critical temperature in layered superconductors

Bąk Z.

Prace Naukowe. Chemia / Wyższa Szkoła Pedagogiczna w Częstochowie

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2003

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Vol. 8

115--119

EN

We consider Bose-Einstein condensation of preexisting Cooper pairs which are confined within quasi-2D laminar structure. We show that the spectral dimensionality ɑ of such systems should be described within fractional-dimensional scheme. From detailed calculations results that for ɑ > 3 results that one would expect enhancement of critical temperature up to the limit set by the Cooper pair binding energy. We show that in the laterally modulated systems there can arise ɑ > 3 case while for the optimally doped YBCO system there is experimental evidence that ɑ =4.

4

Vortices in the underdoped layered superconductors

Lenkowska-Czerwińska T.

Journal of Technical Physics

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2003

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Vol. 44, no 4

403-408

EN

We analyze the vortex core structure in the stripe phase of underdoped layered superconductors. The stripes arise primarily from charge-spin separation in a low-dimensional system. Coexistence of charge (hole-rich) and spin (hole-poor) nanodomains and superconductivity has been reported in recent years. Recently, the local density of states modulation around a vortex core has been found. The modulation indicates a competing type of order that can coexist with superconductivity. The idea is that where the superconducting order is suppressed in the core of a vortex, the competing order can be manifested. We analyze the competing orders on the basis of the Ginzburg-Landau theory. Finally, we note that the existence of competing orders gives rise to vortices that effectively have two core radii defined by the superconducting and charge coherence length.