Hysteresis model for polycrystalline high-<i>T</i>
                  <i>c</i> superconductors

Stancil, Daniel D.; Schlesinger, T. E.; Stamper, A. K.; Wong, Derek Chi Kian

doi:10.1063/1.342195

Cited by 19 publications

(4 citation statements)

References 15 publications

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“…where α(x) is the tilt angle of B(x) with respect to the z axis. Since in our flux cutting measurements H a > H c1 , where we let H c1 denote the lower critical field for both the high-T c grains and also for the PbIn slab, the magnetic induction (5) just inside the surfaces of the idealized specimens satisfies the boundary conditions…”

Section: Framework For the Analysismentioning

confidence: 99%

“…The majority of these measurements have been carried out on samples subjected to a magnetic field changing only in magnitude. The high-T c superconductors behave as hard superconductors and, therefore, their magnetic response under such conditions has been well described with models [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] based on the well known Bean critical state concept [16].…”

Section: Introductionmentioning

confidence: 99%

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Flux-line cutting in granular high-T_cand semi-reversible classical type-II superconductors

Pérez-Rodrı́guez

LeBlanc

Gandolfini

2001

Supercond. Sci. Technol.

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The magnetic responses of granular (NdBa2Cu3O7-x and YBa2Cu3O7-x) and monolithic (PbIn) superconducting plates, cooled in a fixed magnetic field Hz parallel to their plane and, later, subjected to cycles of a transverse magnetic field Hy with an amplitude Hy,max>Hz, are investigated both experimentally and theoretically. Magnetization curves, generated as Hy with Hz constant applied and of the order of the full penetration field Hp, are interpreted by employing two competing models (the double critical-state model and the two-velocity hydrodynamic model) for describing flux-line cutting effects on the magnetic behaviour of superconductors. Both models qualitatively and semi-quantitatively reproduce the experimental curves. Unlike the double critical-state model, the two-velocity hydrodynamic approach predicts the appearance of zones with homogeneous magnitude of the magnetic induction B at relatively small values of Hy as |Hy| is increased. However the effect of these zones is not appreciable since they disappear when |Hy| reaches a sufficiently large value: |Hy| ≳ Hz≈Hp.

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Section: Framework For the Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Flux-line cutting in granular high-T_cand semi-reversible classical type-II superconductors

Pérez-Rodrı́guez

LeBlanc

Gandolfini

2001

Supercond. Sci. Technol.

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“…Because of their distribution function, the grain size is typically known only within a factor of 10 [6]. Thus, the model should give accurate values within an order of magnitude, but should also exhibit the correct qualitative behaviour.…”

Section: U CM -3 and Jc(t H) In A Cm -2 M T (T H) -M (T H) Is Thmentioning

confidence: 97%

Resistive and magnetic properties of Y1−x Zr x Ba2Cu3O7−δ and Y1−2x Zr x Eu x Ba2Cu3O7−δ superconductive compounds

Burzo

Pop²

1992

J Mater Sci

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The results of X-rays, electrical resistivities and magnetic studies performed on Y1-xZrxBa2Cu307-6 and Y1-2xZrxEuxBa2Cu307 s superconducting compounds, in the temperature range 4.2-500 K and external fields up to 50 kOe are reported. The presence of zirconium decreases the superconducting transition temperatures, T c. Below Tc, the hysteresis loops narrow when the zirconium content increases. From the magnetization curves, the critical current densities were determined. A time dependence of the magnetizations of logarithmic form was found. The flux-pinning energy was estimated to be U -~ 0.03 eV. Above the transition temperatures, Y1-xZrxBa2Cu307-~ samples show a Pauli-type paramagnetism, while Y1-2xZr, EuxBa2Cu307 ~ compounds have, in addition, temperature-dependent contributions to the magnetic susceptibilities. The effective europium moments are --~ 3.40 ~1, B suggesting that the ion is in ( 4-3) valence state.

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“…Since the equation requires the value of H c2 , this was obtained from the magnetization curves taken at different temperatures. The reversible magnetization was obtained from the hysteresis loops using the standard prescription [28], after incorporating the superconducting fraction η = 0.22. The intermediate field equation [29]…”

Section: ρ Ff As a Function Of Hmentioning

confidence: 99%

Modified flux flow in polycrystalline YBCO: temperature and current dependence

Asim¹,

Hasanain²

1996

Supercond. Sci. Technol.

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DC resistivity of a zero-field-cooled granular YBCO sample has been studied as a function of angle between the applied field and transport current, at various fields, currents and temperatures. In addition to the large angle-independent dissipation, a small angle-dependent part has been observed which has a sin 2 θ behaviour. This part varies with increasing fields according to a modified flux flow expression, in line with the reported microwave surface resistance data. Interestingly, the exponent, n, of the field dependence obtained from a modified flux flow expression gives values close to the one at low currents and low temperatures, whereas it reduces towards 0.5 for large values of currents and temperatures close to T c . With increasing current and temperature, the behaviour of the flux flow in YBCO approaches that which has been reported for BSCCO. The behaviour is considered to be due to a decrease of the coherence of vortex segments at higher currents and temperatures. Furthermore, the deviation of the voltage from sin 2 θ at low angles has also been studied at different currents and temperatures, which further supports our previous conjecture of Lorentz-force-mediated flux redistribution between inter-and intragrain regions.

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Hysteresis model for polycrystalline high-T c superconductors

Cited by 19 publications

References 15 publications

Flux-line cutting in granular high-T_cand semi-reversible classical type-II superconductors

Flux-line cutting in granular high-T_cand semi-reversible classical type-II superconductors

Resistive and magnetic properties of Y1−x Zr x Ba2Cu3O7−δ and Y1−2x Zr x Eu x Ba2Cu3O7−δ superconductive compounds

Modified flux flow in polycrystalline YBCO: temperature and current dependence

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Hysteresis model for polycrystalline high-T c superconductors

Cited by 19 publications

References 15 publications

Flux-line cutting in granular high-Tcand semi-reversible classical type-II superconductors

Flux-line cutting in granular high-Tcand semi-reversible classical type-II superconductors

Resistive and magnetic properties of Y1−x Zr x Ba2Cu3O7−δ and Y1−2x Zr x Eu x Ba2Cu3O7−δ superconductive compounds

Modified flux flow in polycrystalline YBCO: temperature and current dependence

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Product

Resources

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Flux-line cutting in granular high-T_cand semi-reversible classical type-II superconductors

Flux-line cutting in granular high-T_cand semi-reversible classical type-II superconductors