Evidence for anisotropic triplet superconductor order parameter in half-metallic ferromagnetic La0.7Ca0.3Mn3O proximity coupled to superconducting Pr1.85Ce0.15CuO4

Abstract

Scanning tunneling spectroscopy measurements performed on La0.7Ca0.3Mn3O (LCMO) films epitaxially grown on Pr1.85Ce0.15CuO4 (PCCO) reveal localized penetration of superconductivity into the LCMO up to distances much larger than is possible for Cooper pairs in a singlet spin state to exist. This long-range proximity effect is manifested in the tunneling spectra as gaps and, less abundantly, as zero-bias conductance peaks (ZBCPs). Since ZBCPs were not found on the bare PCCO films, their appearance is attributed to an anisotropic (p wave or d wave) triplet-pairing superconductor order parameter induced in the LCMO.