Determination of current and flux distribution in squares of thin-film high-temperature superconductors

Grant, P. D.; Denhoff, M. W.; Xing, Weirong; Brown, P.; Govorkov, S. A.; Irwin, J. C.; Heinrich, B.; Zhou, Hua; Fife, A. A.; Cragg, A.

doi:10.1016/0921-4534(94)90509-6

Cited by 44 publications

(23 citation statements)

References 12 publications

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“…[10][11][12][13][27][28][29][30][31][32] The most remarkable difference is that shielding currents flow along the entire width of the sample including the flux-free region whereby the field component perpendicular to the surface is equal to zero. Direct magnetooptical observations of the flux distributions in wide superconducting strips subjected to an external field 33 or carrying a transport current 34 and current distributions extracted from such data 35 are in good agreement with theoretical predictions. 12,13 Before we begin with the study of flux distributions in magnetically shielded hard superconductors it is necessary to resume the main features of the partly flux-filled state of an isolated superconductor strip.…”

Section: Partly Flux-filled Hard Superconductor Strips In a Flat supporting

confidence: 63%

Overcritical states of a superconductor strip in a magnetic environment

2000

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A current-carrying superconducting strip partly penetrated by magnetic flux and surrounded by a bulk magnet of high permeability is considered. Two types of samples are studied: those with critical current controlled by an edge barrier dominating over the pinning, and those with high pinning-mediated critical current masking the edge barrier. It is shown for both cases that the current distribution in a central flux-free part of the strip is strongly affected by the actual shape of the magnetic surroundings. Explicit analytical solutions for the sheet current and self-field distributions are obtained which show that, depending on the geometry, the effect may suppress the total loss-free transport current of the strip or enhance it by orders of magnitude. The effect depends strongly on the shape of the magnet and its distance to the superconductor but only weakly on the magnetic permeability.

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Section: Partly Flux-filled Hard Superconductor Strips In a Flat supporting

confidence: 63%

Overcritical states of a superconductor strip in a magnetic environment

2000

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“…These profiles enable one to reconstruct the spatial distribution of the sheet currents J flowing in the sample 1,2, 3,4,5,6,7,8 (the sheet current J is the current density integrated over the thickness of the sample), and hence to extract some information on the critical currents in the superconductor. 9 The magneticfield profiles are measured either with magneto-optical imaging, 10,11,1 or with Hall-sensor arrays.…”

Section: Introductionmentioning

confidence: 99%

Anisotropic superconducting strip in an oblique magnetic field

Brandt

Mikitik

2005

Phys. Rev. B

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The critical state of a thin superconducting strip in an oblique applied magnetic field Ha is analyzed without any restrictions on the dependence of the critical current density jc on the local magnetic induction B. In such a strip, jc is not constant across the thickness of the sample and differs from Jc/d, where Jc is the critical sheet current. It is shown that in contrast to the case of B-independent jc, the profiles Hz(x) of the magnetic-field component perpendicular to the strip plane generally depend on the in-plane component Hax of the applied magnetic field Ha, and on how Ha is switched on. On the basis of this analysis, we explain how and under what conditions one can extract jc(B) from the magnetic-field profiles Hz(x) measured by magneto-optical imaging or by Hall-sensor arrays at the upper surface of the strip.

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“…In the sand-pile model, it is assumed that a current flows along the edge to form a squaie loop. Grant and co-workers [8] determined current and field distribution in squares of thin-film sample using an array of equal sized circulating current cells. However, no work has been done on the field distribution using a large rectangular bulk.…”

Section: Introductionmentioning

confidence: 99%

Observation of flux distribution on the surface of MPMG-processed YBCO

Higuchi

Sakai

Murakami

et al. 1995

IEEE Trans. Appl. Supercond.

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A macroscopic observation of a magnetic flux distribution on the surface of a superconducting bulk material was performed. First, a single-domained thin rectangular YBCO sample (10 mmxl0mmxlmm) was field-cooled in liquid nitrogen. After the applied field was turned off, a field distribution in the area of lOmmxlOmm was mapped by scanning the sample surface at intervals of 0. 5" using a Hall probe fixed to a XY-stage. The obtained field distribution was visualized into a three-dimensional distribution map and a twodimensional contour graph. The overall shape of the field distribution had a four-fold symmetry reflected by the sample geometry. Next, assuming that the critical current density J , is independent of the field strength, a field distribution generated by square current loops was calculated numerically. The intragranular J, was estimated to be 2.6x1@A/cm2 (77K, OT) by fitting the calculated profile to the measured profile. Finally, it is found that the measurement of field distributions on the surface of a superconductor using a Hall probe is applicable to an estimation of an ntragranular J , for a superconductor without destroying the samples.

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Determination of current and flux distribution in squares of thin-film high-temperature superconductors

Cited by 44 publications

References 12 publications

Overcritical states of a superconductor strip in a magnetic environment

Overcritical states of a superconductor strip in a magnetic environment

Anisotropic superconducting strip in an oblique magnetic field

Observation of flux distribution on the surface of MPMG-processed YBCO

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