Determination of two-dimensional current patterns in flat superconductors from magneto-optical measurements: An efficient inversion scheme

Wijngaarden, Rinke J.; Spoelder, H.J.W.; Surdeanu, R.; Griessen, R.

doi:10.1103/physrevb.54.6742

Cited by 94 publications

(64 citation statements)

References 16 publications

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“…The function f is determined in a separate calibration experiment, while ␤ can be found by relating the intensity with the field at a certain location in the image where the field is known, e.g., far away from the sample, where the local magnetic field is equal to the applied external field. 36 Images were taken using a liquid-nitrogen-cooled ST-138 CCD Camera ͑Princeton Instruments͒.…”

Section: Experiments and Sample Preparationmentioning

confidence: 99%

Crossover between fractal and nonfractal flux penetration in high-temperature superconducting thin films

et al. 1998

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In this study the role of anisotropy on flux penetration in c-axis epitaxial Tl 2 Ba 2 CuO 6ϩx and YBa 2 Cu 3 O 7Ϫx films is investigated by magneto-optics. We study thin films of Tl 2 Ba 2 CuO 6ϩx on substrates with vicinal angles of 0°͑well-oriented͒, 0.5°, 2.5°, and 4°and YBa 2 Cu 3 O 7Ϫx films as a function of chain-conduction-induced anisotropy. A crossover from fractal to nonfractal flux penetration is observed with increasing anisotropy. Numerical simulations of anisotropic flux motion are compared with experiment. ͓S0163-1829͑98͒05742-7͔

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Section: Experiments and Sample Preparationmentioning

confidence: 99%

Crossover between fractal and nonfractal flux penetration in high-temperature superconducting thin films

et al. 1998

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“…(Here I shall not list numerous recent work on mesoscopically small superconductors with vortices computed from GinzburgLandau theory.) An elegant and fast method that computes the currents in films from the magnetic field pattern measured at the film surface with high resolution, without having to store or explicitly invert a large matrix, is described by Wijngaarden et al;11,12 this method has all advantages of the direct matrix inversion method and avoids the inversion by Fourier transform, that would require knowledge of the magnetic field pattern also outside the film area. The static Bean model for thin films of any shape is computed by Prigozhin using a variational method.…”

Section: Introductionmentioning

confidence: 99%

Thin superconductors and SQUIDs in perpendicular magnetic field

Brandt

2005

Phys. Rev. B

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It is shown how the static and dynamic electromagnetic properties can be calculated for thin flat superconducting films of any shape and size, also multiply connected as used for SQUIDs, and for any value of the effective magnetic London penetration depth Λ. As examples, the distributions of sheet current and magnetic field are obtained for rectangular and circular films without and with slits and holes, in response to an applied perpendicular magnetic field and to magnetic vortices moving in the film. The self energy and interaction of vortices with each other and with an applied magnetic field and/or transport current are given. Due to the long ranging magnetic stray field, these energies depend on the size and shape of the film and on the vortex position even in large films, in contrast to the situation in large bulk superconductors. The focussing of magnetic flux into the central hole of square films without and with a radial slit is compared.

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“…2-4. Most experimental studies of flux penetration, see e. g. Refs. [5][6][7][8], are focused on the behavior of samples placed in an external magnetic field, as well as on the remanent state after the field is switched-off. The results appear in a good agreement with experiment.…”

Section: Introductionmentioning

confidence: 99%

Magneto-optical study of magnetic-flux penetration into a current-carrying high-temperature-superconductor strip

et al. 1999

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Magnetic flux distribution across a high-temperature superconductor strip is measured using magneto-optical imaging at 15 K. Both the current-carrying state and the remanent state after transport current are studied up to the currents 0.97Ic where Ic is the critical current. To avoid overheating of the sample current pulses with duration 50 ms were employed. The results are compared with predictions of the Bean model for the thin strip geometry. In the current-carrying state, reasonable agreement is found. However, there is a systematic deviation -the flux penetration is deeper than theoretically predicted. A much better agreement is achieved by accounting for flux creep as shown by our computer simulations. In the remanent state, the Bean model fails to explain the experimental results. The results for the currents I ≤ 0.7Ic can be understood within the framework of our flux creep simulations. However, after the currents I > 0.7Ic the total flux trapped in a strip is substantially less than predicted by the simulations. Furthermore, it decreases with increasing current. Excessive dissipation of power in the annihilation zone formed in the remanent state is believed to be the source of this unexpected behavior.

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Determination of two-dimensional current patterns in flat superconductors from magneto-optical measurements: An efficient inversion scheme

Cited by 94 publications

References 16 publications

Crossover between fractal and nonfractal flux penetration in high-temperature superconducting thin films

Crossover between fractal and nonfractal flux penetration in high-temperature superconducting thin films

Thin superconductors and SQUIDs in perpendicular magnetic field

Magneto-optical study of magnetic-flux penetration into a current-carrying high-temperature-superconductor strip

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