Butterfly magnetization in YBa{sub 2}Cu{sub 3{minus}{ital x}}Fe{sub {ital x}}O{sub 7{minus}{ital y}}: Correlation with the microstructure and the macrostructure
- Laboratoire de Physique des Solides (associe au CNRS, URA 0002), Universite Paris-Sud, 91405 Orsay Cedex (France)
- Departement de Physique, Universite de Constantine, Constantine (Algeria)
- EDF, 1, Avenue du General de Gaulle, 92141 Clamart Cedex (France)
The butterfly anomaly in the critical current density ({ital J}) of a large number of YBa{sub 2}Cu{sub 3{minus}{ital x}}Fe{sub {ital x}}O{sub 7{minus}{ital y}} samples is investigated as a function of the magnetic field (0{le}{ital H}{le}60 kOe), the field sweep rate (2 Oe/s{le}{ital dH}/{ital dt}{le}10{sup 3} Oe/s), the temperature ({ital T}{le}55 K), the dimensions of the specimens (10{sup {minus}2} mm{le}{ital R}{le}0.6 mm), and their microstructures. The magnitude and the shape of the central peak of {ital J}({ital H}) depend strongly on the size of the specimen, but only weakly on its microstructure. Despite the differences in the defect structures of the various samples, their current densities tend towards the same value for {ital R}{le}50 {mu}m, {ital T}{lt}60 K, and {ital H}{le}{ital H}{sub {ital m}2}, with {ital H}{sub {ital m}2} denoting the field of the second maximum of the hysteresis cycle. The latter field generally decreases with the defect concentration ({ital n}{sub {ital ef}}) and provides an excellent characterization of the pinning properties of the material. At low concentration, the pinning force increases with {ital n}{sub {ital ef}}, while the pinning barriers decreases. The butterfly effect is consistent with the collective creep theory in the field region around {ital H}{sub {ital m}2}. This field marks a crossover between small and large bundle pinning regimes. {copyright} {ital 1996 The American Physical Society.}
- OSTI ID:
- 283902
- Journal Information:
- Physical Review, B: Condensed Matter, Vol. 53, Issue 18; Other Information: PBD: May 1996
- Country of Publication:
- United States
- Language:
- English
Similar Records
Vortex correlations in the superconducting transition of YBa[sub 2](Cu[sub 1[minus][ital x]]Al[sub [ital x]])[sub 3]O[sub 7[minus][delta]] films in high magnetic fields
Influence of oxygen stoichiometry on the irreversible magnetization and flux creep in {ital R}Ba{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} ({ital R}=Y,Tm) single crystals