Self-organized critical state in High-Tc superconductors

Ling, Xinsheng; Shi, Donglu; Budnick, J.L.

doi:10.1016/0921-4534(91)91215-p

Cited by 19 publications

(4 citation statements)

References 10 publications

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“…The nonlinear diffusion equations (8.4) and (8.4a) are closely related to the concept of 'self-organized criticality' (Bak et ai 1988, Jensen 1990, Pla and Non 1991, Ling et al 1991, Richardson erai 1994, DeGennes 1966) and to Gurevich's idea of the universality of flux creep (section 9.8), or to problems with logarithmic time scale , Vinokur et al 1991a, van der Beek et al 1993. From the universal electric field during creep E ( r , t ) = F ( r ) / t (Gurevich and Kiipfer 1993, Gurevich andBrandt 1994) it follows that (8.4) is a linear da$Tusion equation in the logarithmic time T = Int since D -El/t.…”

Section: H(x T ) = C[ (H')"]' -And(t) ( 8 4 ~)mentioning

confidence: 99%

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The flux-line lattice in superconductors

1995

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Magnetic flux can penetrate a type-II superconductor in form of Abrikosov vortices (also called flux lines, flux tubes, or fluxons) each carrying a quantum of magnetic flux φ 0 = h/2e. These tiny vortices of supercurrent tend to arrange in a triangular flux-line lattice (FLL) which is more or less perturbed by material inhomogeneities that pin the flux lines, and in high-T c superconductors (HTSC's) also by thermal fluctuations. Many properties of the FLL are well described by the phenomenological Ginzburg-Landau theory or by the electromagnetic London theory, which treats the vortex core as a singularity. In Nb alloys and HTSC's the FLL is very soft mainly because of the large magnetic penetration depth λ: The shear modulus of the FLL is c 66 ∼ 1/λ 2 , and the tilt modulus c 44 (k) ∼ (1 + k 2 λ 2 ) −1 is dispersive and becomes very small for short distortion wavelength 2π/k ≪ λ. This softness is enhanced further by the pronounced anisotropy and layered structure of HTSC's, which strongly increases the penetration depth for currents along the c-axis of these (nearly uniaxial) crystals and may even cause a decoupling of two-dimensional vortex lattices in the Cu-O layers. Thermal fluctuations and softening may "melt" the FLL and cause thermally activated depinning of the flux lines or of the two-dimensional "pancake vortices" in the layers. Various phase transitions are predicted for the FLL in layered HTSC's. Although large pinning forces and high critical currents have been achieved, the small depinning energy so far prevents the application of HTSC's as conductors at high temperatures except in cases when the applied current and the surrounding magnetic field are small.

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Section: H(x T ) = C[ (H')"]' -And(t) ( 8 4 ~)mentioning

confidence: 99%

“…experiments of Fhbrega et al (1994a). For more work on the 'fish-tail effect' see Ling and Budnick (1991), Kohayashi et a1 (1993), Klupsch et a1 (1993). Gordeev etal (1994).…”

Section: Universality Offlux Creepmentioning

confidence: 99%

The flux-line lattice in superconductors

1995

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“…¿From a dynamic point of view, there has been considerable interest and speculation about systems of the type under investigation here possibly exhibiting selforganized criticality (SOC) when driven to the threshold of instability. Many discussions of SOC in pinned flux lattices have relied on measurements or investigations of systems relaxing away from criticality [8,9], making them less than ideally suited for examining the SOC hypothesis. In our work, the system is truly driven to the threshold of instability and then allowed to organize itself into a critical state.…”

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confidence: 99%

Confirmation of the modified Bean model from simulations of superconducting vortices

1994

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¿From a very simple description of vortices and pinning centers and without using any electrodynamical assumptions, we obtain nonlinear density profiles of vortices in type-II dirty superconductors that result from raising or lowering an external magnetic field. The results confirm a modified Bean model description of these systems, and in particular, follow the Kim empirical form that relates the current inside the material to the local magnetic field. We also obtain realistic magnetization hysteresis loops and examine the discrete evolution of the density profiles in our systems. This evolution is not continuous, but takes place by the occurrence of avalanches of vortices promoted by the addition or extraction of vortices from the edges of the system. 74.60.Ge, 05.60.+w 1

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“…To deal with realistic flux motion in a wide range of driving forces, new dynamical theories are needed. In our previous work [8][9][10], we have proposed that the vortex state is a typical spatially and temporally extended system and can well be described in the framework of self-organized criticality (SOC) [11][12][13]].…”

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confidence: 99%

Transport resistive broadening by avalanche flux motion in high-temperature superconductors: SOC in a driven system

Wang

Shi

1994

Solid State Communications

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The subrrilled manusor_hasbeenauthored byI a contractor d theU.S.Government under I contract No.W-31-109-ENG-38. Accordingly, I theU.S.Government retainsa nonexcluslve, I royalty-tree license to publish orreproduce the I published formofthiscontflbutlon, or allow I otherstodoso,for U.S.Government purposes. I DISCLAIMER This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or jmc process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.

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Self-organized critical state in High-Tc superconductors

Cited by 19 publications

References 10 publications

The flux-line lattice in superconductors

The flux-line lattice in superconductors

Confirmation of the modified Bean model from simulations of superconducting vortices

Transport resistive broadening by avalanche flux motion in high-temperature superconductors: SOC in a driven system

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