Combinatorial sputtering in planetary type systems for alloy libraries with perpendicular gradients of layer thickness and composition realised by a timing approach

Abstract

We present a combinatorial sputtering technique to fabricate alloy thin films with orthogonal gradients of thickness and stoichiometry in a planetary type sputtering system. Using this approach we prepared a library of planar Nb Josephson junctions with a magnetic compound layer made from Si and Fe on one wafer. The independent investigation of thickness and composition changes of the Fe$_x$Si$_{1-x}$ layer allows the identification of transition regions where the phase difference of the superconducting order parameter across the barrier changes from 0 to $\pi$. A mapping technique which allows to identify the different coupling regimes depending on material properties might facilitate the fabrication of $\pi$ junctions with tailored critical current, damping and normal resistance parameters for applications.