Magnetic field dependence of the proximity-induced triplet superconductivity at ferromagnet/superconductor interfaces

Long-ranged superconductor proximity effects recently found in superconductor-ferromagnetic (S-F) systems are generally attributed to the formation of triplet-pairing correlations due to various forms of magnetic inhomogeneities at the S-F interface. In order to investigate this conjecture within a single F layer coupled to a superconductor, we performed scanning tunneling spectroscopy on bilayers of La2/3Ca1/3MnO3 (LCMO) ferromagnetic thin-films grown on high temperature superconducting films of YBa2Cu3O7- (YBCO) or Pr1.85Ca0.15CuO4 (PCCO) under various magnetic fields. We find a strong correlation between the magnitude of superconductor-related spectral features measured on the LCMO layer and the degree of magnetic inhomogeneity controlled by the external magnetic field. This corroborates theoretical predictions regarding the role played by magnetic inhomogeneities in inducing triplet-pairing at S-F interfaces.This research was supported in parts by the joint German-Israeli DIP Project (G.K. and O.M.), the United States-Israel Binational Science Foundation (O.M.), the Harry de Jur Chair in Applied Science (O.M.), the Karl Stoll Chair in advanced materials at the Technion (G.K.), the Leverhulme Trust through an International Network Grant (J.W.A.R., M.G.B. and O.M.) and the Royal Society (J.W.A.R.).This is the accepted manuscript version. The final published version is available from the publishers at http://journals.aps.org/prb/abstract/10.1103/PhysRevB.89.180506. © 2014 AP