We consider a long diffusive Josephson junction where the weak link is a thin normal metal (N) – ferromagnetic (F) bilayer (N and F form parallel links between the superconductors (S)). We show that superconductivity in the weak link can be described by an effective one-dimensional Usadel equation containing a “diluted” exchange field as well as a weak depairing term that is caused by the inherent inhomogeneity of the bilayer. The depairing mechanism distinguishes the S(N/F)S system from an SFS junction and affects the density of states of the S(N/F)S junction. It results in the suppression of the minigap in the spin-resolved density of states. The depairing rate and the minigap are expressed in terms of geometrical parameters, the Thouless energy and the effective exchange field. The effective one-dimensional theory can be applied to various structures with thin inhomogenous links and shows good agreement with numerical solutions of the original two-dimensional equations. We also discuss ways to reveal the predicted effect experimentally.

我们考虑一个长扩散约瑟夫森结，其中弱连接是薄的普通金属（N）-铁磁（F）双层（N和F在超导体（S）之间形成平行连接）。我们表明，可以通过一个有效的一维Usadel方程来描述弱连接中的超导性，该方程包含“稀释的”交换场以及由双层固有的不均匀性引起的弱的去配对项。取消配对机制将S（N / F）S系统与SFS结区别开来，并影响S（N / F）S结的状态密度。它导致自旋分辨态密度的最小间隙得到抑制。减车率和最小间隙用几何参数，hou能量和有效交换场表示。有效的一维理论可以应用于具有薄的不均匀连接的各种结构，并且与原始二维方程的数值解具有很好的一致性。我们还讨论了通过实验揭示预测效果的方法。