Transport properties of YBa2Cu3Oy/Nd0.7Sr 0.3MnO3 (YBCO/NSMO) multilayers and YBa2Ca3Oy/PrBa2Cu3O y (YBCO/PBCO) superlattices were measured to characterize the activation energy and the upper critical field. The activation energy of the superconducting multilayers decreases as the thickness of the NSMO layer or the PBCO layer becomes thicker and the superconducting YBCO layer gets thinner. Temperature-dependence of upper critical fields shows a crossover from three-dimensional (3D) to two-dimensional (2D) behavior in YBCO/NSMO multilayers as the thickness of the YBCO layer is decreased. The results are discussed.
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