Magnetic-coherence-length scaling in metallic multilayers

An improved description of the critical properties of metallic multilayers is obtained by introducing the concept of a scaled magnetic coherence length in the Takahashi-Tachiki theory. By that, the absolute magnitude of the upper critical fields and the position of the dimensional crossover are uncoupled and become independent quantities. Much better phase diagrams can be obtained by using this scaling procedure. Although this concept is inspired by the character of disagreement between the theory without scaling and experiment, the procedure lacks an external justification. The fact that it works might serve as an indication how the Takahashi-Tachiki theory has to be modified in order to give a realistic quantitative description of upper critical fields in real metallic multilayers. The theory is applied to the V/Cu, V/Ag, Nb/Cu, and Nb/Ag systems.