Surface barrier and lower critical field in YBa2Cu3O7−δ superconductors
D.-X. Chen, R. B. Goldfarb, R. W. Cross, A. Sanchez
DOI 10.1103/PhysRevB.48.6426 · Physical Review B
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Abstract
The fields for the first vortex entry and last vortex exit, H1 and H2, and the lower critical field Hc1 for a grain-aligned, sintered YBa2Cu3O7−δ superconductor have been determined from saturated magnetic-hysteresis loops using an extended critical-state model. For fields oriented along the grain c axis, H1 increases with decreasing temperature, showing an upturn below 50 K, whereas H2 remains small and positive, in general agreement with the theory of Bean-Livingston surface barriers. Hc1 has a Bardeen-Cooper-Schrieffer temperature dependence above 50 K, but it rises at low temperatures. For fields oriented in the ab plane, Hc1 has a similar temperature dependence, but surface barriers are not evident in the magnetization.
Source-reported materials — not catalogue approval
| Formula | Reported Tc (K) | Pressure (GPa) | Type |
|---|---|---|---|
| YBa2Cu3O7-δ Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | — | Pressure not reported | unknown |
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