The effect of barrier thickness and interface resistance upon the critical currents of YBa2Cu3O7−δ/noble metal/conventional superconductor junctions

✍ Scribed by H.W. Lean; E.J. Tarte; J.R. Waldram; Z.H. Barber; R.E. Somekh

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 445 KB
• Volume: 224
• Category: Article
• ISSN: 0921-4534
• DOI: 10.1016/0921-4534(94)90255-0

✦ Synopsis

We report a study of the critical current I¢ of YBa2Cu307_6 (YBCO)/noble metal/conventional superconductor structures with noble-metal thicknesses in the range 20 nm to 1 ~tm and resistance-area products R~/between 10 -9 fl cm 2 and 10 -5 fl cm 2. Good agreement was found between the temperature dependence of Ic and the predictions of a simple proximity-effect theory which assumed that there was no degraded layer between the YBCO and the noble metal. The magnitude of/c, corrected for the sample temperature and noble-metal thickness using the theory, was found to scale with R; ~ . These observations are shown to be consistent with a model in which the YBCO/noble metal interface is highly nonuniform with the total area of low-resistance contact making up only a small fraction of the total junction area. This explains the large interface resistivities observed in the YBCO/noble metal system.