Magnetism and superconductivity in oxide ferromagnet/superconductor heterostructures

We report on the transport and magnetic properties of La0.67Sr0.33MnO3/YBa2Cu3O7/La0.67Sr0.33MnO3 (LSMO/YBCO/LSMO) trilayer structures. The onset of superconducting transition temperature in trilayer structures starts from the sample with 6 nm (5 unit cells) thick YBCO layer. M(H) hystersis loop indicate indirect exchange coupling between LSMO layers across YBCO layer. MR studies demonstrate a change of magnetoconductance (MC) of a trilayer structure with variation of magnetic field, indicating an indirect exchange coupling between LSMO layers across nonsuperconducting YBCO layer.