Superconducting upper critical fields of V/Cr-superlattices

✍ Scribed by Y. Kuwasawa; Y. Kamata; T. Watanabe; S. Nakano; S. Matuda

• Publisher: Elsevier Science
• Year: 1992
• Tongue: English
• Weight: 425 KB
• Volume: 190
• Category: Article
• ISSN: 0921-4534
• DOI: 10.1016/0921-4534(92)90615-j

✦ Synopsis

In V/Cr-superlattices, the superconducting transition temperature and upper critical fields are investigated for the superlattices of various Cr-layer thicknesses (tic, = 20-90 A ) under a constant V-layer thickness (dr = 300 A ). These samples are prepared by UHV-deposition at 300 and 500°C onto the V-buffer layer that is grown on the sapphire substrates heated upto 500°C. The dependence of critical temperature on the Cr-layer thickness obeys the fits calculated by the Werthamer model for the films deposited at 300°C. A dimensional crossover in the parallel upper critical fields was observed in the samples deposited at 300°C and was not found in the films done at 500°C. Such a crossover is shown in the superlattices with dcr_ < 50 A and occurs when the effective superconducting layer thickness becomes comparable to the perpendicular coherence length ¢~ at the crossover points.