Two superconductors held together by a thin layer of insulator allow the flow of supercurrent induced by the phase difference of the Cooper pair wave functions. This effect was predicted by B. Josephson and it has found a number of practical applications (e.g. in SQUID interferometers for extremely sensitive detection of magnetic fields). It has been shown more recently that tunneling of Cooper pairs also occurs through a single atom or a molecule due to the formation of bound states induced by multiple Andreev reflections. The direction and intensity of the Josephson current under such conditions are determined by the competition of the superconducting proximity effect with the Coulomb repulsion (leading to the so-called "zero-pi transition").The prospect of using the Josephson effect seems also possible in planar junctions, where the superconductors are separated by a thin metallic layer with a width of the order of micrometers. The cooperation of the proximity effect and Rashba type interaction leads to the appearance of a topologically non-trivial phase, which was confirmed by experimental results. In the talk I will present the special features of this system and indicate an alternative topological scenario of superconductivity based on the self-organization of magnetic moments in the metallic layer.

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