Critical state of an YBa2Cu3Ox strip in a perpendicular magnetic field as revealed by a scanning ESR probe

Khasanov, R.; Talanov, Yu. I.; Vashakidze, Yu.; Teǐtel'Baum, G. B.

doi:10.1016/0921-4534(94)02421-9

Cited by 14 publications

(4 citation statements)

References 17 publications

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“…Comparing the ESR-signal shift at the point over the sample center with the magnitude of H* obtained from the dependence of AHR(y = 0) on Hco in [16], it turns out that for ZFC case AHR(0) is many times larger than H*. It follows that our experimental results cannot be described in the framework of the Bean model of the critical state.…”

Section: Zero Field Coolingcontrasting

confidence: 41%

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Scanning ESR-microprobe studies of the flux distribution in type-II superconductors

1998

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A new method for the study of the distribution of the magnetic field in a superconducting sample is developed. The field profile in the interior of the sample is mapped from the data on the spin probe ESR-signal shift measured at different points over the plane surface. The main attention is focused to the penetration of a perpendicular magnetic field into single crystal strips. The penetration of magnetic flux into an YBCO crystal is shown to be delayed and this gives rise to formation of the steep fronts in the profile of the field near the center of the strip. The profile observed differs considerably from the well-known Bean picture. It is highly dependent on the magnetic history. For the case of a Bi:2212 rectangular crystal, the crossover of the magnetic field profile from a dome shape, typical for a geometrical barrier (T > 30 K), to a bulk pinning picture (T < 25 K) was observed upon variation of temperature. The analysis of the field distribution made it possible to determine the temperature dependence of the lower critical field.

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Section: Zero Field Coolingcontrasting

confidence: 41%

“…Scanning the microprobe over the superconducting sample one can determine the magnetic field induction at any point from the ESR-signal shift and then reconstruct the magnetic field profile inside the sample. (Our first experimental results on this problem were published for YBa2Cu3OX compound in [ 16] and for Bi2 Sr,CaCu2Oy in [17]. )…”

Section: Introductionmentioning

confidence: 99%

Scanning ESR-microprobe studies of the flux distribution in type-II superconductors

1998

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“…Rogacki et al (1995) confirm the magnetization curve (8.9) by the vibrating reed technique. The field profile (8.8) is confirmed, e.g., by magneto-optics (Schuster et al 1994d), by Hall probes (Zeldov et al 1994b), and by an electron-spin resonance microprobe (Khasanov et al 1995), see also section 1.2.…”

Section: Extension To Transverse Geometrymentioning

confidence: 66%

The flux-line lattice in superconductors

1995

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Magnetic flux can penetrate a type-II superconductor in form of Abrikosov vortices (also called flux lines, flux tubes, or fluxons) each carrying a quantum of magnetic flux φ 0 = h/2e. These tiny vortices of supercurrent tend to arrange in a triangular flux-line lattice (FLL) which is more or less perturbed by material inhomogeneities that pin the flux lines, and in high-T c superconductors (HTSC's) also by thermal fluctuations. Many properties of the FLL are well described by the phenomenological Ginzburg-Landau theory or by the electromagnetic London theory, which treats the vortex core as a singularity. In Nb alloys and HTSC's the FLL is very soft mainly because of the large magnetic penetration depth λ: The shear modulus of the FLL is c 66 ∼ 1/λ 2 , and the tilt modulus c 44 (k) ∼ (1 + k 2 λ 2 ) −1 is dispersive and becomes very small for short distortion wavelength 2π/k ≪ λ. This softness is enhanced further by the pronounced anisotropy and layered structure of HTSC's, which strongly increases the penetration depth for currents along the c-axis of these (nearly uniaxial) crystals and may even cause a decoupling of two-dimensional vortex lattices in the Cu-O layers. Thermal fluctuations and softening may "melt" the FLL and cause thermally activated depinning of the flux lines or of the two-dimensional "pancake vortices" in the layers. Various phase transitions are predicted for the FLL in layered HTSC's. Although large pinning forces and high critical currents have been achieved, the small depinning energy so far prevents the application of HTSC's as conductors at high temperatures except in cases when the applied current and the surrounding magnetic field are small.

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“…Several methods are used to obtain the flux density distribution in superconducting materials, e.g. scanning Hall probe [1,2] and electron spin resonance probe [3] microscopies. However, the magneto-optical(MO) Faraday effect is a powerful method that can provide high-resolution information on the local flux distribution and critical current in high-T c superconductors over a range of important temperatures.…”

Section: Introductionmentioning

confidence: 99%

Visualization of magnetic flux distribution in Bi(Pb)-2223/Ag multifilamentary tapes

Lin

Cochrane

Russell

et al. 1998

Supercond. Sci. Technol.

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The high-resolution magneto-optical technique has been used to visualize the magnetic flux distribution in Bi(Pb)-2223/Ag multifilamentary tapes. Topographies of the magnetic flux will be presented for a seven-element x-array filamentary distribution which has both exposed and silver-sheathed filaments. This study was over the temperature range 40-80 K for applied magnetic fields in the range 0-560 G and direct currents up to 60 A. Analysis of the visual patterns will be presented and in the case of the x-array compared with the work of Mawatari (1996 B 54 13 215) and Müller (1997 Physica C 289 123).

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Critical state of an YBa2Cu3Ox strip in a perpendicular magnetic field as revealed by a scanning ESR probe

Cited by 14 publications

References 17 publications

Scanning ESR-microprobe studies of the flux distribution in type-II superconductors

Scanning ESR-microprobe studies of the flux distribution in type-II superconductors

The flux-line lattice in superconductors

Visualization of magnetic flux distribution in Bi(Pb)-2223/Ag multifilamentary tapes

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