Hysteretic depinning and dynamical melting for magnetically interacting vortices in disordered layered superconductors (original) (raw)
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Driven vortices in 3D layered superconductors: Dynamical ordering along the c-axis
We study a D model of driven vortices in weakly coupled layered superconductors with strong pinning. Above the critical force Fc, we find a plastic flow regime in which pancakes in different layers are uncoupled, corresponding to a pancake gas. At a higher F, there is an "smectic flow" regime with short-range interlayer order, corresponding to an entangled line liquid. Later, the transverse displacements freeze and vortices become correlated along the c-axis, resulting in a transverse solid. Finally, at a force Fs the longitudinal displacements freeze and we find a coherent solid of rigid lines. PACS numbers: 74.60.Ge, 74.40.+k, 05.70.Fh It is well-known that an external current can induce an ordering of the vortex structure in superconductors with pinning (1). For a long time, it was believed that the high-current phase would have crystalline order. Re- cently, it has been found that different kinds of order are possible at high currents, depending on pinning strength and...
Driven vortices in three-dimensional layered superconductors: Dynamical ordering along the c axis
Physical Review B, 2000
We study a 3D model of driven vortices in weakly coupled layered superconductors with strong pinning. Above the critical force Fc, we find a plastic flow regime in which pancakes in different layers are uncoupled, corresponding to a pancake gas. At a higher F , there is an "smectic flow" regime with short-range interlayer order, corresponding to an entangled line liquid. Later, the transverse displacements freeze and vortices become correlated along the c-axis, resulting in a transverse solid. Finally, at a force Fs the longitudinal displacements freeze and we find a coherent solid of rigid lines.
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Europhysics Letters (EPL), 1997
We report results for a 3D simulation of a layered superconductor. There are two significant temperatures. The first corresponds to melting of the vortex lattice in the a-b plane (T ab) and the second to decoupling of the layers (T dc) with T ab ≤ T dc. The decoupling is found to be a first order transition with an associated entropy of ∼ 0.25 − 0.4kB/pancake. The melting has no obvious thermodynamic signature, and could be a crossover. The width of the intermediate regime T ab < T < T dc , decreases with increasing anisotropy such that for the more anisotropic system we cannot distinguish the melting and decoupling temperatures.
Physica C: Superconductivity, 1997
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Anisotropic Vortices in High-Temperature Superconductors: Precursor Effects
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In our recent papers we have found that a three-dimensional superconducting state with anisotropic vortices localized at the vortex-lattice points is a stable state in zero and nonzero external magnetic field for the layered hightemperature superconductivity materials. There exists a phase transition at the temperature T v c from the normal phase to the vortex superconducting state which is of the first order. Note that the transition is in zero magnetic field. The first order phase transition shows overheating and overcooling effects. Nucleation of the superconducting phase in the normal phase thus may occur at temperatures higher than the transition temperature T v c. Then the onset of the vortex-like excitations above the transition temperature T v c occurs in our theory. The onset of the vortex-like excitations in Nerst signal and some other experimental evidence for these excitations above the transition temperature T v c in LSCO, YBCO and in other similar high-temperature materials may be explained thus by our theory. The vortex-like excitations above and below the transition temperature T v c in LSCO, YBCO and in other similar high-temperature materials continuously evolve. This fact may be explained within our theory.
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