Vortex entry conditions in type-II superconductors.

Vodolazov, D. Yu.; Maksimov, I. L.; Brandt, Ernst Helmut

doi:10.1016/s0921-4534(02)01877-4

Cited by 63 publications

(47 citation statements)

References 21 publications

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“…28 It is shown in Refs. 16,8, and 29 that this expression derived from the Maxwell-London equations fits over a broad range of parameters with the Ginzburg-Landau solutions for the screening-current distribution as long as H < H en . Moreover, measurements of the magnetic field profile crossing the sample border when the sample is prepared in the Meissner state can be well fitted using the current distribution in Eq.…”

Section: Discussionmentioning

confidence: 76%

“…In order to achieve this goal, a careful sample design and fabrication are necessary. First, the presence of surface defects may create spots for premature entry of vortices, 4,15,16 thus influencing the study of the intrinsic mechanisms. Second, in thin-film geometry, vortices will move to the center of the sample as soon as they nucleate, 17 making it impossible to experimentally observe their entry.…”

Section: Thatmentioning

confidence: 99%

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First vortex entry into a perpendicularly magnetized superconducting thin film

et al. 2013

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In type-II superconductors, the flux-free state (Meissner state) may be invaded by vortices bearing quantized flux once H is above the lower critical field H c1 . However, the actual first flux penetration does not occur at H c1 due to the presence of a surface barrier and the fact that the Meissner state may also exist as a metastable state up to a larger (superheating) field. In this work we determine the field for the first vortex penetration in superconductors by directly imaging the first vortex threading a superconducting Pb film with antidots. We find that the first vortex penetration occurs when the surface superconducting currents reach the depairing current, locally breaking superconductivity and allowing a vortex to nucleate.

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Section: Discussionmentioning

confidence: 76%

Section: Thatmentioning

confidence: 99%

First vortex entry into a perpendicularly magnetized superconducting thin film

et al. 2013

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“…This discrepancy between theory and experiment can be explained by a more rapid decrease of j c when increasing temperature, as compared to the difference H 2 − H 1 between the first penetration fields at the indentation and at the smooth border. Vodolazov et al 39 have investigated theoretically the influence of sample defects in the penetration of vortices in a homogeneous superconductor. These authors concluded that the presence of surface defects causes a drop in the first penetration field and leads to a qualitative change in the magnetization curve.…”

Section: Ported Theoreticallymentioning

confidence: 99%

Magnetic flux penetration in Nb superconducting films with lithographically defined microindentations

et al. 2016

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We present a thorough investigation by magneto-optical imaging of the magnetic flux penetration in Nb thin films with lithographically defined border indentations. We demonstrate that discontinuity lines (d-lines), caused by the abrupt bending of current streamlines around the indentations, depart from the expected parabolic trend close to the defect and depend on the shape and size of the indentation as well as on the temperature. These findings are backed up and compared with theoretical results obtained by numerical simulations and analytical calculations highlighting the key role played by demagnetization effects and the creep exponent n. In addition, we show that the presence of nearby indentations and submicrometer random roughness of the sample border can severely modify the flux front topology and dynamics. Strikingly, in contrast to what has been repeatedly predicted in the literature, we do not observe that indentations act as nucleation spots for flux avalanches, but they instead help to release the flux pressure and avoid thermomagnetic instabilities.

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“…Internal bulk properties can likewise lead to more complicated states as in two-band superconductors described by a two-component Ginzburg-Landau model [11]. In a number of articles the influence of surface defects has been investigated [12][13][14]. For a regular superconducting disk, the energy barrier has been calculated by Berdiyorov et al [10] for a single vortex to enter or exit the disk.…”

mentioning

confidence: 99%