Magneto-Optical Studies of Magnetization Processes in High-Tc Superconductors

Vlasko-Vlasov, Vitalii; Crabtree, G. W.; Welp, U.; Никитенко, В. И.

doi:10.1007/978-94-011-4558-9_8

Cited by 27 publications

(25 citation statements)

References 255 publications

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“…They illustrate the creation of a typical pillow-shaped pattern (Fig.1a-b) due to the magnetic flux entry from the sample edges (brighter contrast corresponds to larger normal field B ⊥ ). The shape of the pattern arises from strong field screening by the sharp supercurrent turns at diagonals of the sample corners (see Fig.1c) and is usually observed in high-quality thin rectangular superconducting plates and films [23]. A deeper flux penetration from the top sample side compared with the lower sample side in Figure 1b indicates a lower edge barrier for the vortex entry at the top side.…”

Section: Magnetization In Perpendicular Field After Zero-field Coolingmentioning

confidence: 78%

“…The crystal is mostly untwined, apart from a few narrow twins located near one corner. The sample was placed on top of a cold finger in an optical cryostat and spatial maps of the normal induction B ⊥ on the sample surface were imaged with a polarized light microscope using a magneto-optical (MO) indicator film technique [23]. Values of B ⊥ were obtained from the intensity, I, of the MO images using I(B ⊥ ) calibration.…”

Section: Methodsmentioning

confidence: 99%

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Flux cutting in high-Tcsuperconductors

et al. 2015

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We performed magneto-optical study of flux distributions in a YBCO crystal under various applied crossed-field orientations to elucidate the complex nature of magnetic flux cutting in superconductors. Our study reveals unusual vortex patterns induced by the interplay between flux-cutting and vortex pinning. We observe strong flux penetration anisotropy of the normal flux B ⊥ in the presence of an in-plane field H || and associate the modified flux dynamics with staircase structure of tilted vortices in YBCO and the flux-cutting process.We demonstrate that flux-cutting can effectively delay vortex entry in the direction transverse to H || . Finally, we elucidate details of the vortex-cutting and reconnection process using time-dependent Ginzburg-Landau simulations.

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Section: Magnetization In Perpendicular Field After Zero-field Coolingmentioning

confidence: 78%

Section: Methodsmentioning

confidence: 99%

Flux cutting in high-Tcsuperconductors

et al. 2015

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“…This technique shows visually the position of cracks [5,8], weak links [4,6,7] and other micro-and macroscopic defects in the sample [2,9], however there may be other current-limiting mechanisms that are not so readily visible at the macroscopic scale nor directly dependent on critical current density [10,11].…”

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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“…We used our Magneto-optic (MO) indicator technique [19] to directly image the normal-flux dynamics in the sample at T<T c while cycling the magnitude of the perpendicular magnetic field, H z . The Py stripes were polarized along different directions within the film plane by applying an in-plane magnetic field H || (20 to 150 Oe) at T>T c .…”

Section: Sample and Experimentsmentioning

confidence: 99%

Manipulating Abrikosov vortices with soft magnetic stripes

Vlasko-Vlasov

Colauto

Buzdin³

et al. 2017

Phys. Rev. B

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Tuning the polarization of a periodic array of magnetic stripes on top of a superconducting film allows control of Abrikosov vortex motion. Using direct magneto-optical imaging of the vortex patterns, we demonstrate that the proximity of the magnetic stripe ends to the edges of the superconducting film can strongly alter the vortex dynamics. We observe qualitatively different vortex behavior when the stripes overlap with the film edges. From the resulting unique magnetic flux patterns, we calculate the magnetic pinning strength of our stripe array and study effects of the modified edge barrier on vortex guidance and gating that result from different polarizations of the stripes .

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Magneto-Optical Studies of Magnetization Processes in High-Tc Superconductors

Cited by 27 publications

References 255 publications

Flux cutting in high-Tcsuperconductors

Flux cutting in high-Tcsuperconductors

Dynamic magneto-optical imaging of superconducting thin films

Manipulating Abrikosov vortices with soft magnetic stripes

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