Critical state in superconducting single-crystalline YBa2Cu3O7 foams: Local versus long-range currents
E. Bartolomé, X. Granados, T. Puig, X. Obradors, E. S. Reddy, G. J. Schmitz
DOI 10.1103/PhysRevB.70.144514 · Physical Review B
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Abstract
The establishment of the critical state in single-crystalline YBa2Cu3O7 foams, a new kind of porous superconducting material, has been analyzed by using Hall probe magnetic imaging and hysteresis cycles. We evidence that superconducting foams display a critical state composed of a background magnetization linked to the total dimension of the sample, superposed to many additional magnetic flux peaks related to the pore structure of the foam. The observed magnetization maps can be described by an “effective,” long-range critical-current density extending over the whole sample and a local critical-current density associated with small current loops. The values of the effective critical current density are mainly determined by the amount of porosity. The magnetic field dependence of the local and effective critical-current densities are found to be the same and independent on sample porosity, indicating that vortex pinning is the only physical microscopic mechanism ruling the critical currents in these materials.
Source-reported materials — not catalogue approval
| Formula | Reported Tc (K) | Pressure (GPa) | Type |
|---|---|---|---|
| YBa2Cu3O7 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 77 | Pressure not reported | unknown |
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