Trapping and relaxation of inter- and intragrain vortices in YBa2Cu3O7−δ

Blinov, E. V.; Lähderanta, E.; Laiho, R.; Stepanov, Yu. P.

doi:10.1016/0921-4534(92)90560-y

Cited by 15 publications

(9 citation statements)

References 32 publications

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“…At the lowest temperatures, a typical Anderson-Kim-like logarithmic dependence was observed. (figure 11), in agreement with previous investigations of intergranular flux creep [25][26][27]. In figure 12 we plot the field dependence of the normalized relaxation rate; several features associated with the different characteristic H (T ) lines in the magnetic phase diagram (figure 5) may be distinguished.…”

Section: Flux Dynamicssupporting

confidence: 87%

Magnetic flux penetration and creep in a ceramic superconductor

Pérez

Obradors

Fontcuberta

et al. 1996

Supercond. Sci. Technol.

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A magnetic study has been carried out on a Y 0.5 Sm 0.5 Ba 2 Cu 3 O 7−δ ceramic sample, which showed a high intergrain connectivity. A.C. susceptibility, d.c. magnetization and low-field hysteresis loop measurements have been performed with the aim of determining the characteristic superconducting parameters involved in a ceramic superconductor: lower critical fields (H J c1 and H g c1 ), penetration depths (λ J and λ g ), penetration fields (H * J and H * g ), critical currents (J J c , J g c ) and irreversibility fields (H J ir and H g ir ). We experimentally confirm the validity of the two-level critical state analysis for the interpretation of the intergranular and intragranular magnetic flux effects in ceramic samples and we propose a methodology to define the magnetic phase diagram of the sample. A consistent picture of all the magnetic flux effects is obtained by analysing the intergranular flux effects in terms of an array of Josephson junctions. Flux creep associated with the Josephson vortices is detected and the effective activation energy is found to be consistent with a Josephson vortex creep model.

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Section: Flux Dynamicssupporting

confidence: 87%

Magnetic flux penetration and creep in a ceramic superconductor

Pérez

Obradors

Fontcuberta

et al. 1996

Supercond. Sci. Technol.

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“…We also address pertinent observations by several other workers [9][10][11][12][13][14] on the relaxation rates of magnetization where the initial field profiles correspond to that displayed in figure 1(b) or figure 1(d ) and compare these data with the predictions of our model.…”

Section: Introductionsupporting

confidence: 59%

“…These data should be compared with the initial portions of the theoretical curves displayed in figure 7. In our view and as noted by Blinov et al [1,9,18] and Fleisher et al [19], the difference between the experimental and theoretical curves in the low-field region arises because our simple model ignores H C1 . Hence our model neglects the feature that some flux adjacent to the surfaces of the particles is expelled during the field cooling and that the flux density profiles, after the removal of the applied field H 0 ≤ H C1 (T f ) H * (T f ), have zones where j is subcritical even before the magnetic relaxation commences [20][21][22].…”

Section: Display Data For M a Versus H F Cmentioning

confidence: 47%

“…Blinov et al [9] also report on the evolution of the initial rate of magnetic relaxation observed for configuration B over the low-field range 0 < H 0 H * * (T ) (see figure 3(b) of [9]). The low-field region of our figure 5 should be compared with, and are seen to describe satisfactorily, the corresponding data of Blinov et al [9].…”

Section: Display Data For M a Versus H F Cmentioning

confidence: 98%

“…Blinov et al [9] report on the evolution versus H 0 of M B , the spatial average of the magnetic field trapped in a small particle specimen by procedure B. In that paper, Blinov et al display the growth of M B over the entire low-field S-shaped region and the plateau of M B which is observed when the excursion of H 0 exceeds the 'double' penetration field H * * (see figure 2(d ) of [9]). The latter is the amplitude of the applied field sweep needed to establish flux-retaining currents circulating around the entire volume of the specimen after its removal [23,24].…”

Section: Display Data For M a Versus H F Cmentioning

confidence: 99%

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Effect of the configuration of the trapped flux on the decay rate of remanent magnetic moments in type II superconductors

LeBlanc

Cameron

Çelebi

et al. 1998

Supercond. Sci. Technol.

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Several workers have measured the rates of decay of remanent magnetic moments in granular high- superconductors where the temperature-field histories generated trapped flux profiles comprising two concentric regions of countercirculating persistent currents. Exploiting a simple model based on the critical state for bulk specimens and the conservation of flux for the redistribution of vortices, and neglecting , we account for the major features of these observations although in some cases the number of trapped vortices is small. The model makes readily testable predictions of the relative magnitudes of the initial rates of magnetic relaxation for various configurations of flux density profiles.

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Quantum creep of Josephson intergrain vortices in Bi2Sr2Ca2Cu3O10

Moehlecke

Kopelevich

1997

J Low Temp Phys

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Magnetic relaxation caused by the creep of Josephson intergrain vortices is studied in Bi2Sr2Ca2Cu3010 high-T c superconductor in (Physica C 222 (1994) 149). PACS numbers: 74.60.Ge, 74.80.Bj, 74.72.Hs Recently, it was shown by various groups that the classical thermally activated creep of Abrikosov vortices in high-T c superconductors (HTS) is changed to a quantum creep with lowering temperature 1. The experimental results could be well understood within the quantum collective creep theory in the limit of strong dissipation 2 or Hall tunneling theory 3. On the other hand, the phenomenon of macroscopic quantum tunneling (MQT) occurring in Josephson junctions systems such as the superconducting quantum interference device (SQUID) or Josephson-junctions arrays has always attracted a great experimental 4-6 and theoretical 7-10 interest. To our best knowledge, however, there are no reports on MQT occurring either in artificially grown HTS-based Josephson junctions or in the Josephson medium of polycrystalline HTS.The investigation of a possible quantum tunneling of Josephson intergrain vortices in HTS ceramics is the subject of the present work.We have studied the magnetic relaxation caused by the creep of Josephson intergrain vortices in Bi2Sr2Ca2Cu3010 (Bi: 2223) polycrystalline sample, and found that at high enough temperatures the normalized logarithmic 207 0022-2291/97/0200-0207512.50/0 9 1997 Plenum Publishing Corporation

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Trapping and relaxation of inter- and intragrain vortices in YBa2Cu3O7−δ

Cited by 15 publications

References 32 publications

Magnetic flux penetration and creep in a ceramic superconductor

Magnetic flux penetration and creep in a ceramic superconductor

Effect of the configuration of the trapped flux on the decay rate of remanent magnetic moments in type II superconductors

Quantum creep of Josephson intergrain vortices in Bi2Sr2Ca2Cu3O10

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