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Measurements of the temperature dependence of the magnetic penetration depth in YBa sub 2 Cu sub 3 O sub 7 minus. delta. superconducting thin films

Journal Article · · Physical Review, B: Condensed Matter; (United States)
; ; ; ;  [1]
  1. Department of Applied Physics, Stanford University, Stanford, California (USA)

Using a very sensitive microstrip-resonator technique, we have measured {lambda}({ital T}) of {ital c}-axis YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} films on various substrates and compared the results to similar data on Nb and NbCN films. For YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}}, {lambda}({ital T}) is found to be exponential and not power law in its temperature dependence (for {ital T}{lt}{ital T}{sub {ital c}}/2) in the best films. Overall the data cannot be described by a single-gap BCS temperature dependence. The data at low temperature provide a lower limit of 2{Delta}(0)/{ital k}{sub {ital B}T{ital c}}{approx}2.5 for the minimum gap in Yba{sub 2}Cu{sub 3}O{sub 7{minus}{delta}}, yet show strong-coupling-like behavior at high temperatures. We discuss our results in the context of other experiments on the cuprate superconductors.

OSTI ID:
6188050
Journal Information:
Physical Review, B: Condensed Matter; (United States), Journal Name: Physical Review, B: Condensed Matter; (United States) Vol. 44:17; ISSN PRBMD; ISSN 0163-1829
Country of Publication:
United States
Language:
English