MAGNETIC-COHERENCE-LENGTH SCALING IN METALLIC MULTILAYERS

An improved description of the critical properties of metallic multila yers is obtained by introducing the concept of a scaled magnetic coher ence length in the Takahashi-Tachiki theory. By that, the absolute mag nitude of the upper critical fields and the position of the dimensiona l crossover are uncoupled and become independent quantities. Much bett er phase diagrams can be obtained by using this scaling procedure. Alt hough this concept is inspired by the character of disagreement betwee n the theory without scaling and experiment, the procedure lacks an ex ternal justification. The fact that it works might serve as an indicat ion how the Takahashi-Tachiki theory has to be modified in order to gi ve a realistic quantitative description of upper critical fields in re al metallic multilayers. The theory is applied to the V/Cu, V/Ag, Nb/C u, and Nb/Ag systems.