$\mathbf{\pi}$-junction realization due to the tunneling through thin ferromagnetic layer

It is demonstrated that in superconductor-ferromagnet-superconductor (S/F/S) systems in the case of low interface transparency the transition into $\pi $-phase is not related with the oscillations of the superconducting order parameter in F-layer. In consequence the $\pi $-phase may exist at very thin F-layer thickness. The crossover from $\pi $-to $0$-phase results in the non-monotonous temperature dependence of the critical current.