Magnetization and Critical Supercurrents

Kim, Y. B.; Hempstead, C. F.; Strnad, A. R.

doi:10.1103/physrev.129.528

Cited by 795 publications

(207 citation statements)

References 8 publications

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“…The magnetization process is usually described in terms of the Bean model [29] and its generalizations: flux lines enter into the sample and, due to the presence of quenched disorder, give rise to a steady flux gradient. While the Bean model provides a consistent picture of average magnetization properties, such as the hysteresis loop and thermal relaxation effects [30], it does not account for local fluctuations in time and space. It has been recently observed that flux line dynamics is intermittent, taking place in avalanches [31], and flux fronts are not smooth [32][33][34].…”

Section: Gradient Driven Dynamics: Front Invasionmentioning

confidence: 99%

Deblocking of interacting particle assemblies: from pinning to jamming

Miguel¹,

Andrade²,

Zapperi³

2003

Braz. J. Phys.

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A wide variety of interacting particle assemblies driven by an external force are characterized by a transition between a blocked and a moving phase. The origin of this deblocking transition can be traced back to the presence of either external quenched disorder, or of internal constraints. The first case belongs to the realm of the depinning transition, which, for example, is relevant for flux-lines in type II superconductors and other elastic systems moving in a random medium. The second case is usually included within the so-called jamming scenario observed, for instance, in many glassy materials as well as in plastically deforming crystals. Here we review some aspects of the rich phenomenology observed in interacting particle models. In particular, we discuss front depinning, observed when particles are injected inside a random medium from the boundary, elastic and plastic depinning in particle assemblies driven by external forces, and the rheology of systems close to the jamming transition. We emphasize similarities and differences in these phenomena.

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Section: Gradient Driven Dynamics: Front Invasionmentioning

confidence: 99%

Deblocking of interacting particle assemblies: from pinning to jamming

Miguel¹,

Andrade²,

Zapperi³

2003

Braz. J. Phys.

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“…Magneto-Optical Imaging (MOI) is generally carried out under static field conditions with a constant applied DC field [2,[12][13][14][15][16]. MOI investigations into vortex dynamics or other "dynamic" effects in superconductors typically deal with AC fields [17,18], or simply consider the effect of changing the magnetic sweep rate on the final stable state [19].…”

Section: Introductionmentioning

confidence: 99%

Dynamic magneto-optical imaging of superconducting thin films

Wells

Pan

Wilson

et al. 2016

Supercond. Sci. Technol.

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We present a novel method for analysis of superconducting thin films using dynamic magneto-optical imaging, revealing hallmarks of flux penetration with temporal resolution around 1 ms (in the present work) or better. This method involves investigation of transient field and dynamic current distributions, which are calculated by an inversion procedure on the Biot-Savart Law, which we show to be valid under dynamic conditions. We compare and discuss the flux front penetration speed and evolution of current distribution in high quality YBa2Cu3O${}_{7-\delta }$ thin films with that of samples deliberately damaged in such a way as to reduce critical current density without causing macroscopic damage. We present a novel method for analysis of superconducting thin films using dynamic magnetooptical imaging, revealing hallmarks of flux penetration with temporal resolution around 1 ms (in the present work) or better. This method involves investigation of transient field and dynamic current distributions, which are calculated by an inversion procedure on the Biot-Savart Law, which we show to be valid under dynamic conditions. We compare and discuss the flux front penetration speed and evolution of current distribution in high quality YBa2Cu3O7−δ thin films with that of samples deliberately damaged in such a way as to reduce critical current density without causing macroscopic damage.

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“…This fact and the strong dependence of J c ðBÞ produce an asymmetric M(H) loop with higher magnetization values in the lower branch. As has been suggested in the earlier work of Kim,20 the average magnetic field in the upper and lower branches can be estimated by hBi ' l 0 H 6 MðHÞ=2 and a quasisymmetric loop MðhBiÞ can be obtained. For fields l 0 H $ 1T and higher, where the creep studies are performed, the difference between hBi and l 0 H in all the samples becomes negligible; therefore, the relaxation study and sample comparison can be done at fixed H.…”

Section: Resultsmentioning

confidence: 74%

Carbon nanotubes effects on the relaxation properties and critical current densities of MgB2 superconductor

Pasquini

Serquis

Moreno

et al. 2013

Journal of Applied Physics

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Addition of nonsuperconducting phases, such as carbon nanotubes, can modify the superconducting properties of MgB 2 samples, improving the critical current density and upper critical field. A full understanding of the flux creep mechanism involved is crucial to the development of superconducting magnets in persistent mode, one of the main thrusts for the development of MgB 2 wires. In this paper we present a creep study in bulk MgB 2 samples, pure and with different amounts of carbon nanotubes additions. We conclude that the most consistent picture at low temperatures is a single vortex pinning regime, where the correlation length is limited by the grain size. We introduce a novel analysis that allows us to identify the region where the Anderson-Kim model is valid. V C 2013 AIP Publishing LLC. [http://dx

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Magnetization and Critical Supercurrents

Cited by 795 publications

References 8 publications

Deblocking of interacting particle assemblies: from pinning to jamming

Deblocking of interacting particle assemblies: from pinning to jamming

Dynamic magneto-optical imaging of superconducting thin films

Carbon nanotubes effects on the relaxation properties and critical current densities of MgB2 superconductor

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