Critical states in 2D disk-shaped type-II superconductors in periodic external magnetic field

Zhu, Jianguo; Mester, John; Lockhart, J. M.; Turneaure, J. P.

doi:10.1016/0921-4534(93)90506-l

Cited by 128 publications

(48 citation statements)

References 13 publications

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“…This model was corrected and extended by Zhu et al who showed that since the current density cannot change discontinuously in interior of the film, magnitude of the current density decreases continuously in vortex-free annulus from j c to zero in center of the disk [4]. Because of large aspect ratio of 2D disk in perpendicular field, parallel with z axis, the flux density bends around the disk and shielding currents flow over the entire surface of the disk.…”

Section: Methodsmentioning

confidence: 99%

“…The holder was suspended on both thermally and electrically insulating support which was connected to stainless steel tube. This insert was placed in anti-cryostat filled with 4 He gas at atmospheric pressure. Temperature of the anti-cryostat was controlled by Si diode temperature sensor, Lake Shore temperature controller, and resistive wire heater.…”

Section: Methodsmentioning

confidence: 99%

“…The magnetization curves were computed using the complete analytical solution to the magnetization of the 2D disk-shaped superconductor in time-varying applied field [4], [5]. When the external field varies periodically with amplitude H ac , the magnetization is ( )…”

Section: B Calculation Of Magnetization Curvesmentioning

confidence: 99%

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Analysis of Critical State Response in Thin Films by AC Susceptibility Measurements

Youssef

Švindrych

Hadač

et al. 2008

IEEE Trans. Appl. Supercond.

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Abstract-Low frequency ac magnetic response of the Nb thin film in perpendicular oscillating applied fields is detected by continuously reading SQUID magnetometer. Harmonic analysis of the temperature dependence of the nonlinear ac susceptibility gives excellent agreement with the susceptibility calculated on basis of model of the hysteretic critical state in 2D disk. This complete analytical model relates to Bean's critical state described by the critical depinning current density. We map the experimental and model data and we trace the temperature dependence of the critical current density. The model fits up to temperature 0.9997T c above which nonlinear response turns to linear one. This technique is also suitable for characterization of HTS thin films.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Analysis of Critical State Response in Thin Films by AC Susceptibility Measurements

Youssef

Švindrych

Hadač

et al. 2008

IEEE Trans. Appl. Supercond.

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“…In general the flux and current distribution in the superconductor is influenced by the sample geometry, the external magnetic field and the critical current density j c (B,r). Penetration of perpendicular flux into thin superconductors has recently been calculated analytically, within the Bean assumption jр j c and without an influence of edge barrier, for thin circular disks 2,3 and long stripes 4 in transverse field, and for strips carrying a transport current, 5 see also the analytical solution for a strip with bulk pinning and edge barrier. 6,7 For a negligible edge barrier, a general two-dimensional equation of motion for the sheet current in a thin planar superconductor of arbitrary shape was given by Gurevich and Brandt.…”

Section: Introductionmentioning

confidence: 99%

Influence of microscopic defects in type-II superconducting thin films on the magnetic flux penetration

et al. 2001

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The magnetic flux penetration into thin type-II superconducting films with circular defects is investigated. The artificial circular defects ͑diameter ϭ40 m) in an YBa 2 Cu 3 O 7Ϫ␦ thin film ͑thickness Ϸ300 nm) were prepared by pulse-laser irradiation. The flux penetration into the zero-field-cooled superconducting film was visualized by means of the magneto-optic method. A stepwise increase of the external magnetic field allowed a detailed investigation of the influence of local defects on the flux penetration. For a magnetic field parallel to a long sample ͑longitudinal geometry͒ with a long cylindrical defect a single parabolic discontinuity line appears. Also in the case of a thin superconducting film exposed to a transverse magnetic field ͑transverse geometry͒, a single parabolic discontinuity line has been supposed in the vicinity of a local defect. On the contrary, our investigations show that the flux and current distribution around a single defect in a superconducting thin film can be determined not by a single, but by two discontinuity parabolas. In thin superconducting films in transverse geometry screening currents in the Meissner region ( jϽ j c ) are present in contrast to extended infinitely long samples in the longitudinal geometry. We explain our experimental results by the influence of these Meissner screening currents on the temporal formation of the shape of an approaching flux front.

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“…For decades, there were many theoretical studies of critical state in thin film characterized by a field-independent J c (Bean model). [3][4][5][6][7][8][9] However, many experiments show that the current J c often depends strongly on the local flux density B in real materials. This dependence often hinders precise interpretation of various measured quantities such as magnetization hysteresis loops and ac-susceptibility 10,11 where the Bean model may be invalid at large field amplitudes and the J c (B) plays a major role.…”

Section: Introductionmentioning

confidence: 99%

Field-dependent critical state of high-Tc superconducting strip simultaneously exposed to transport current and perpendicular magnetic field

Xue

Yong

et al. 2013

AIP Advances

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We present an exact analytical approach for arbitrary field-dependent critical state of high-Tc superconducting strip with transport current. The sheet current and flux-density profiles are derived by solving the integral equations, which agree with experiments quite well. For small transport current, the approximate explicit expressions of sheet current, flux-density and penetration depth for the Kim model are derived based on the mean value theorem for integration. We also extend the results to the field-dependent critical state of superconducting strip in the simultaneous presence of applied field and transport current. The sheet current distributions calculated by the Kim model agree with experiments better than that by the Bean model. Moreover, the lines in the Ia-Ba plane for the Kim model are not monotonic, which is quite different from that the Bean model. The results reveal that the maximum transport current in thin superconducting strip will decrease with increasing applied field which vanishes for the Bean model. The results of this paper are useful to calculate ac susceptibility and ac loss.

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Critical states in 2D disk-shaped type-II superconductors in periodic external magnetic field

Cited by 128 publications

References 13 publications

Analysis of Critical State Response in Thin Films by AC Susceptibility Measurements

Analysis of Critical State Response in Thin Films by AC Susceptibility Measurements

Influence of microscopic defects in type-II superconducting thin films on the magnetic flux penetration

Field-dependent critical state of high-Tc superconducting strip simultaneously exposed to transport current and perpendicular magnetic field

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