The critical current density in high fields in epitaxial thin films of Y1Ba2Cu3O7−δ : Flux pinning and pair breaking
1992; American Institute of Physics; Volume: 72; Issue: 9 Linguagem: Inglês
10.1063/1.352325
ISSN1520-8850
AutoresDamian P. Hampshire, Siu‐Wai Chan,
Tópico(s)Superconducting Materials and Applications
ResumoThe critical current density (Jc) of two epitaxial thin films of Y1Ba2Cu3O7−δ has been measured as a function of temperature in magnetic fields up to 27 T. A detailed study of one of the films shows that when the transport current is in the a-b plane and the magnetic field is orthogonal to the c axis, the functional form of Jc is consistent with both a polynomial (flux pinning) description and an exponential (pair breaking) description. In contrast, when the current is in the a-b plane and the applied field is parallel to the c axis of the film, Jc is unambiguously exponential of the form Jc=α(T)exp[−μ0H/β(T)]. These results explain why there are conflicting suggestions in the literature as to the mechanism that determines Jc in high magnetic fields in thin films for J⊥H⊥c axis and provide evidence that pair breaking operates for J⊥ H∥c axis. However, the standard phenomenological superconductor-normal-superconductor junction model derived in the clean limit for the normal metal cannot describe this pair-breaking mechanism.
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