ISSN:
1434-6036
Source:
Springer Online Journal Archives 1860-2000
Topics:
Physics
Notes:
Abstract We explore the Ginzburg-Landau version of a model for layered superconductors, in which superconducting material consisting ofM unit cells is separated by insulating layers that areN unit cells thick. Invoking the recently proposed interlayer coupling—which enhances pairing within the superconducting sheets—the order parameter coupling turns out to be of Heisenberg type, analogous to layered magnets. The mean field result forT c (M, N) is found to be in remarkable agreement with experiment for ultrathin NbSe2 crystals and Sn−SiO, Al−AlO2, YBCO/PrBCO superlattices. The fact thatT c (M, N) increases with increasingM is traced back to a finite size effect, corresponding to a crossover from nearly two to three-dimensional superconductivity. This change from low to high-temperature superconductivity is found to be independent of the sign of the interlayer interaction. An electrostatic model for the interaction on YBCO/PrBCO superlattices is in reasonable agreement with experiment. The orbital upper critical fieldH c2 ‖ turns out to be unlimited ited whileH c2 ⊥ is proportional toT c (M, N).
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01313399
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