product. At the same time, being placed in external magnetic field $H_{ext}$ SIsFS structure behaves as a single junction, since $d_{s}$ is typically too thin to screen $H_{ext}$. This provides the possibility to switch $J_{C}$ by an external field.

However, theoretical analysis of SIsFS junctions was not performed up to now. The purpose of this paper is to develop a microscopic theory providing the dependence of the characteristic voltage on temperature $T$, exchange energy $H$ in a ferromagnet, transport properties of FS and sF interfaces and thicknesses of s and F layers. Special attention will be given to determining the current-phase relation (CPR) between the supercurrent $J_{S}$ and the phase difference $\varphi $ across the structure.

![ a) Schematic design of SIsFS Josephson junction. b), c) Typical distribution of amplitude $|\Delta (x)|$ and phase difference $\protect\chi (x)$ of pair potential along the structure. []{data-label="design"}](design.eps){width="8.5cm"}

Model of SIsFS Josephson device \[Model\]
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We consider multilayered structure presented in Fig.\[design\]a. It consists of two superconducting electrodes separated by complex interlayer including tunnel barrier I, intermediate superconducting s and ferromagnetic F films. We assume that the conditions of a dirty limit are fulfilled for all materials in the structure. In order to simplify 