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1

Vortices in the inhomogeneous superconducting states of high-Tc superconductivity

Lenkowska-Czerwińska T.

Journal of Technical Physics

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2005

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Vol. 46, no 1

51-59

EN

We investigate the Josephson effect in the stripe phase of in-plane superconductivity of the layered materials. The Ginzburg-Landau model of the mixed in-plane state, s+id, is formulated and the characteristic length scales for the Josephson effect are discussed. The 3D Lawrence-Doniach type model of the stripe state is constructed. The system of equations for the phase of the order parameter is obtained in the London-type approximation. The structure of the pancake and Josephson vortices in the weakly coupled stripes is analyzed.

2

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.

3

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.

4

Alternating states in layered high-T[c] superconductors

Rogula D., Lenkowska-Czerwińska T.

Journal of Technical Physics

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2001

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Vol. 42, no 2

269-274

EN

The coupling between lattice distortion modes and the superconducting order parameters for the layered, high temperature superconductors of La214 class is considered. The set of structural micro-order parameters is determined on the ground of a model of coupled quasi-rigid CuO6 octahedra. The admissible combinations of the superconducting micro-order parameter components are presented. The time reversal symmetry of microscopic and macroscopic states due to correlation between structural and superconducting order parameters is discussed.

5

Structural and superconducting order parameters in the La214 class of high-T[c] superconductors

Lenkowska-Czerwińska T.

Journal of Technical Physics

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1999

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Vol. 40, no 3

373-378

EN

The microscopic distortion order parameters for the tilting modes in a crystal structure like La214 are found, and the macroparameters for the structural phase transition from the tetragonal phase are constructed. Symmetries of a Cooper pair wave function in lattice under distortion are proposed.

6

Structural and superconducting phase transitions in La214 class of high-T[c] superconductors

Lenkowska-Czerwińska T.

Journal of Technical Physics

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1998

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Vol. 39, no 1

155-160

EN

The phase diagram for 214 type high-T[c] superconductors is discussed. The Ginzburg-Landau free energy functional is constructed for structural and superconducting phase transitions. The relation of structural distortion to the critical superconducting temperature is analyzed.

7

Ginzburg-Landau model of high Tc superconductivity

Kotowski R., Lenkowska-Czerwińska T.

Journal of Technical Physics

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1998

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Vol. 39, no 3-4

503-509

EN

In the paper the phenomenological theory of the high-Tc superconductivity in the tetragonal crystals, like La[2]Cu0[4], is discussed. Superconductor described by the two-dimensional (2D), complex value vector order parameter with time-reversal-breaking superconducting states is considered. Superconducting states near the critical points of the second order phase transition are properly described by the phenomenological Ginzburg-Landau free energy functional. Equations describing the order parameters of that states are obtained from the variational principle. The form of that functional depends on the symmetry properties of the considered crystal. The obtained system of the highly nonlinear differential equations for the order parameters and the coupled internal magnetic field is discussed. States with different components of the order parameter can be separated by the domain walls [4]. The soliton-like solutions for such a domain wall are obtained for the specified set of model parameters.