Pinning mechanism of the peak effect in melt-processed Y-123 superconductors

Matsushita, Teruo; Yoshimi, D; Migita, M.; Otabe, Edmund Soji

doi:10.1088/0953-2048/14/9/321

Cited by 12 publications

(5 citation statements)

References 14 publications

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“…4. It is known that the peak effect is caused by the transition of the vortex lattice in Cu oxide superconductors [15]- [18]. However, the reason for the first peak effect in present case is unknown.…”

Section: Resultsmentioning

confidence: 73%

Global and local critical current density in superconducting SmFeAsO1−xFx measured by two methods

Otabe

Kiuchi

Kawai

et al. 2009

Physica C: Superconductivity

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The critical current densities of polycrystalline bulk SmFeAsO 1−x F x prepared by the powder-in-tube (PIT) method and by a conventional solid-state reaction were investigated using the remnant magnetic moment method and Campbell's method. Two types of shielding current, corresponding to global and local critical current densities J c were observed using both measurement methods. The global and local J c were on the order of 10 7 A/m 2 and 10 10 A/m 2 at 5 K, respectively. The local J c decreased slightly with increasing magnetic field. The global J c was independent of the preparation method, while the local J c was larger for samples prepared by PIT than for those prepared by solid-state reaction.

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Section: Resultsmentioning

confidence: 73%

Global and local critical current density in superconducting SmFeAsO1−xFx measured by two methods

Otabe

Kiuchi

Kawai

et al. 2009

Physica C: Superconductivity

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“…ν 0 is the oscillation frequency of the flux bundle in the pinning potential well, and E c is the electric field criterion for determination of J c . Experimental and theoretical values of g 2 in Y-123 superconductor are shown in reference [17] and g 2 mostly takes on values ranging from three to four in a magnetic field parallel to the c-axis. In Bi-2212 single crystals or bulks [18] g 2 is estimated to be smaller than unity using equation (11), and the minimum value, g 2 = 1 for a single flux line, is used.…”

Section: Resultsmentioning

confidence: 99%

Thickness dependence of pinning properties in Bi-2212 superconductor

Matsushita

Yasuda

Wada

et al. 2005

Supercond. Sci. Technol.

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The effect of the thickness of Bi-2212 superconducting thin films and single crystals on the critical current property is investigated in the range of 0.1–10 µm. The peak effect of critical current density at low temperatures disappears for films thinner than the critical thickness in the range of 0.5–1.0 µm. On the other hand, the irreversibility field increases with increasing thickness over the entire range of investigation at low temperatures, suggesting the critical thickness for the irreversibility field is larger than 10 µm. This behaviour is different from that in three-dimensional RE-123 superconductors in which the two critical thicknesses are the same. While the critical thickness for the irreversibility field is given by the pinning correlation length in both types of superconductors, the critical thickness for the peak effect in Bi-2212 seems to be given by the interlayer coupling length. On the other hand, the irreversibility field in the same Bi-2212 specimens is found to decrease with increasing thickness at high temperatures, which is completely opposite to the dependence at low temperatures. This behaviour appears to contradict the theoretical prediction of the flux creep model. However, a detailed investigation reveals that this agrees with the theoretical prediction under the principle of irreversible thermodynamics which describes how the transverse order of flux lines is developed so as to reduce the energy dissipation due to the flux creep for extremely thin films.

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“…In previous measurements [7,8], it was found that J c decreased in the medium field region and the peak effect disappeared through the addition of 211 phase particles to Y-123 bulk superconductor. In addition, Mochida et al [9] found that the peak effect at medium fields decreased through the addition of Nd-422 particles in Nd-123.…”

Section: Introductionmentioning

confidence: 88%

“…In addition, Mochida et al [9] found that the peak effect at medium fields decreased through the addition of Nd-422 particles in Nd-123. This means that the reduction in J cp is ascribed to the interference between the repulsive pinning (positive pinning energy) of lower-T c regions and the attractive pinning (negative pinning energy) of 211 phase particles (Nd-422 or Y-211) [8], suggesting that the pinning mechanism of lower-T c regions is not the attractive one, based on the field-induced pinning mechanism, a kind of condensation energy interaction. The expected mechanism of lower-T c regions is the repulsive kinetic energy interaction under the proximity effect [10].…”

Section: Introductionmentioning

confidence: 99%

Flux pinning properties of (Nd,Eu,Gd)Ba₂Cu₃O_y(NEG-123) superconductor with 211 phase particles

Hasan

Kiuchi

Otabe

et al. 2007

Supercond. Sci. Technol.

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Flux pinning properties were investigated by focusing on the origin of the high peak critical current density and the high irreversibility field for Nd0.33Eu0.38Gd0.28Ba2Cu3Oy (NEG-123) bulk superconductors with the addition of 211 secondary phase particles of volume fractions up to 10 mol%. It was found that a negative correlation exists between the peak critical current density Jcp and the irreversibility field Bi for various fractions of added 211 phase. This suggests that the mechanisms that determine Jcp and Bi are different. The 211 particles do not contribute to the peak effect neither directly through the pinning mechanisms of the condensation energy interaction nor indirectly with the aid of the order–disorder transition of flux lines. Other possible defects are nano-lamella structures. Although these defects do not directly contribute to the peak effect through the pinning mechanism of the condensation energy interaction, they may contribute to it with the aid of the order–disorder transition of flux lines. On the other hand, as Bi deteriorates with the addition of 211 particles, it is not determined by the flux pinning of 211 particles. The decrease in Bi is considered to be caused by the proximity effect of nano-lamella structures.

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Pinning mechanism of the peak effect in melt-processed Y-123 superconductors

Cited by 12 publications

References 14 publications

Global and local critical current density in superconducting SmFeAsO1−xFx measured by two methods

Global and local critical current density in superconducting SmFeAsO1−xFx measured by two methods

Thickness dependence of pinning properties in Bi-2212 superconductor

Flux pinning properties of (Nd,Eu,Gd)Ba₂Cu₃O_y(NEG-123) superconductor with 211 phase particles

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Pinning mechanism of the peak effect in melt-processed Y-123 superconductors

Cited by 12 publications

References 14 publications

Global and local critical current density in superconducting SmFeAsO1−xFx measured by two methods

Global and local critical current density in superconducting SmFeAsO1−xFx measured by two methods

Thickness dependence of pinning properties in Bi-2212 superconductor

Flux pinning properties of (Nd,Eu,Gd)Ba2Cu3Oy(NEG-123) superconductor with 211 phase particles

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Flux pinning properties of (Nd,Eu,Gd)Ba₂Cu₃O_y(NEG-123) superconductor with 211 phase particles