The influence of alloying or interdiffusion on the superconducting properties of ferromagnet/superconductor layered systems

We present the theoretical investigation of alloying or interdiffusion at t he interface on the superconducting properties of ferromagnet/superconducto r (S/F) layered films. The intermixed layer is modeled by the nonsupercondu cting alloy (A) layer, which is characterized by strong scattering on param agnetic impurities. The linearized Usadel equations are derived, which take into account the exchange scattering of excitations on the paramagnetic im purities in the alloyed layer. The superconducting transition temperature o f the S/A/F trilayer is calculated as a function of spin-dependent scatteri ng strength and thickness of A-layer. The nonmonotonic behavior of supercon ducting T, at the onset of ferromagnetism in F-layer is discussed in the fr amework of the presented theory. The oscillations of T. due to ferromagneti c layer thickness variation, and additional influence introduced by an allo y layer, are investigated. (C) 2001 Elsevier Science B.V. All rights reserv ed.