Quasiperiodic metallic multilayers: Growth and superconductivity

We have magnetron-sputtered a series of Mo-V superlattices which have a quasiperiodic layering in the growth direction. We have used the Fibonacci series as the generating rule for the nearly periodic structures and have verified their structure using high-angle x-ray diffractometry. The superconducting transition temperatures slowly increase as a function of the quasiperiodic wavelength ΛF, while the initial upper-critical-field slopes parallel to the films decrease with increasing wavelength, and the parallel upper-critical-field curves H_c2∥ display a two-dimensional behavior that is not consistent with current ideas about critical-field behavior in multilayers.