Magnetic Exchange Fields and Domain Wall Superconductivity at an All-Oxide Superconductor-Ferromagnet Insulator Interface

At a superconductor-ferromagnet (S=F) interface, the F layer can introduce a magnetic exchange field within the S layer, which acts to locally spin split the superconducting density of states. The effect of magnetic exchange fields on superconductivity has been thoroughly explored at S-ferromagnet insulator (S=FI) interfaces for isotropic s-wave S and a thickness that is smaller than the superconducting coherence length. Here we report a magnetic exchange field effect at an all-oxide S=FI interface involving the anisotropic d-wave high temperature superconductor praseodymium cerium copper oxide (PCCO) and the FI praseodymium calcium manganese oxide (PCMO). The magnetic exchange field in PCCO, detected via magnetotransport measurements through the superconducting transition, is localized to the PCCO=PCMO interface with an average magnitude that depends on the presence or absence of magnetic domain walls in PCMO. The results are promising for the development of all-oxide superconducting spintronic devices involving unconventional pairing and high temperature superconductors.S. K., M. G. B., A. D. B., and J. W. A. R. acknowledge funding from the EPSRC through International Network and Programme Grants (No. EP/P026311/1 and No. EP/ N017242/1). J. W. A. R. acknowledges funding from the Royal Society through a University Research Fellowship and with M. G. B. and A. I. B., funding from the Leverhulme Trust and EU Network COST CA16218 (NANOCOHYBRI). A. D. B. acknowledges funding from St. John’s College, Cambridge. S. K. was supported by Grant-in-Aid for JSPS Research Fellows (No. 15J07623)