Ferromagnetism and Superconductivity in CaRuO 3 /YBa 2 Cu 3 O 7-δ Heterostructures.

The deposition of a ferromagnetic layer can affect the properties of high-temperature superconductors underneath. We investigated the influence of ferromagnetic CaRuO 3 on the properties of YBa 2 Cu 3 O 7-x (YBCO) superconducting thin films when the layers are either in direct contact or separated by a barrier layer of 5 nm SrTiO 3 . Detailed measurements of the magnetic moment of the superconductor and ferromagnet as a function of temperature and magnetic field have been performed using SQUID magnetometry. Magnetometry and relaxation measurements show that the modification of the superconducting properties of YBCO strongly depends on the interaction with the ferromagnetic layer on top. The barrier layer has a significant impact on both the supercon-ducting properties of the YBCO film and the ferromagnetic ordering of CaRuO 3 . The physical properties mentioned above were discussed in correlation with the materials' structure determined by XRD analysis.