The very special characteristic of the proximity effect in superconductor-ferromagnet systems is the damped oscillatory behavior of the Cooper pair wave function in a ferromagnet. In some sense, this is analogous to the inhomogeneous superconductivity, predicted long time ago by Larkin and Ovchinnikov (1964), and Fulde and Ferrell (1964), and constantly searched since that. After the qualitative analysis of the peculiarities of the proximity effect in the presence of the exchange field, the author provides a unified description of the properties of the superconductor-ferromagnet heterostructures. Special attention is paid to the striking non-monotonous dependance of the critical temperature of the multilayers and bilayers on the ferromagnetic layer thickness and conditions of the realization of the "Pi"- Josephson junctions. The recent progress in the preparation of the high quality hybrid systems permitted to observe on experiments many interesting effects, which are also discussed in the article. Finally, the author analyzes the phenomenon of the domain-wall superconductivity and the influence of superconductivity on the magnetic structure in superconductor-ferromagnet bilayers.Comment: Submitted to Reviews of Modern Physic

We study the proximity effect between conventional superconductor and magnetic normal metal with a spin-orbit interaction of the Rashba type. Using the phenomenological Ginzburg-Landau theory and the quasiclassical Eilenberger approach it is demonstrated that the Josephson junction with such a metal as a weak link has a special non-sinusoidal current-phase relation. The ground state of this junction is caracterized by the finite phase difference ϕ 0 , which is proportional to the strength of the spin-orbit interaction and the exchange field in the normal metal. The proposed mechanism of the ϕ 0 junction formation gives a direct coupling between the superconducting current and the magnetic moment in the weak link. Therefore the ϕ 0 junctions open interesting perspectives for the superconducting spintronics.Usually the current-phase relations in Josephson junctions near the critical temperature are sinusoidal j(ϕ) = j c sin(ϕ) but with lowering temperature the contribution of the higher harmonic terms ∼ j n sin(nϕ) can be observed. However if the time reversal symmetry is preserved the current-phase relation is always antisymmetric j(−ϕ) = −j(ϕ) [1]. Without this restriction a more general j(ϕ) = j 0 sin(ϕ + ϕ 0 ) dependence is also possible and the generic expression for the current in the pioneering work of Josephson In the present work we demonstrate that the Josephson superconductor/normal metal/superconductor junctions (S/N/S) provides the realization of such unusual current-phase relations j(ϕ) = j 0 sin(ϕ + ϕ 0 ) for the case of conventional superconductors when the normal layer is a non-centrosymmetric, i. e. with broken inversion symmetry (BIS) magnetic metal. Further on we will call this 1

We study the Josephson current through a ferromagnetic trilayer, both in the diffusive and clean limits. For colinear (parallel or antiparallel) magnetizations in the layers, the Josephson current is small due to short range proximity effect in superconductor/ferromagnet structures. For non colinear magnetizations, we determine the conditions for the Josephson current to be dominated by another contribution originating from long range triplet proximity effect.Comment: 4 pages, 2 figure

We report the first experimental observation of the two-node thickness dependence of the critical current in Josephson junctions with a ferromagnetic interlayer. Nodes of the critical current correspond to the transitions into the pi state and back into the conventional 0 state. From the experimental data the superconducting order parameter oscillation period and the pair decay length in the ferromagnet are extracted reliably. We develop a theoretical approach based on the Usadel equations taking into account the spin-flip scattering. Results of numerical calculations are in good agreement with experiments.