Spontaneous currents in a ferromagnet - normal metal - superconductor   trilayer
  We discuss the ground state properties of the system composed of a normal metal sandwiched between ferromagnet and superconductor within a tight binding Hubbard model. We have solved the spin-polarized Hartree-Fock-Gorkov equations together with the Maxwell's equation (Ampere's law) and found a proximity induced Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state in this system. Here we show that the inclusion of the normal metal layer in between those subsystems does not necessarily lead to the suppression of the FFLO phase. Moreover, we have found that depending on the thickness of the normal metal slab the system can be switched periodically between the state with the spontaneous current flowing to that one with no current. All these effects can be explained in terms of the Andreev bound states formed in such structures. 
M. Krawiec, J. F. Annett, B. L. Gyorffy