Magnetic-coherence-length scaling in metallic multilayers

Abstract

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. ͓S0163-1829͑96͒06425-9͔

Influence of the boundary resistivity on the proximity effect

“…[2][3][4][5][6][7] For the first solution, the fitted parameters are close to what one knows from the measurements. However, the dimensional crossover, typical for S/N multilayers, appeared to lie at a much higher temperature than the measured one.…”

Comment on “Magnetic-coherence-length scaling in metallic multilayers”

“…This is what is mimicked by the scaling parameter ␣ in Ref. 1. For all systems where experiments were compared to the infinite layer calculation, a shift to higher temperature is needed, meaning values for ␣ smaller than 1.…”

“…In a recent publication, 1 Koperdraad and Lodder addressed the issue of the behavior of the parallel and perpendicular critical fields in superconductor-normal-metal (S/N) multilayers. Starting from the Takahashi-Tachiki theory, 2 but going beyond the diagonal approximation used in that work ͑see Ref.…”

Model calculations of the proximity effect in finite multilayers

“…In order to prepare a solution to the as yet unsolved problem related to the position of the dimensional crossover in the H c2, (T ) curves, we need to study the way in which nucleation occurs by varying system parameters as well. In addition to the system parameters mentioned already, such as the diffusion constant for S and N layers and the density of states (DOS) of the S layer, we will consider the resistivity of the interfaces [18,19]. Although we start from parameters which are specific to V/Ag, by varying some of them the set we are using might not characterize this system anymore.…”