  Scanning tunneling spectroscopy measurements conducted on epitaxially grown
bilayers of half-metallic ferromagnetic La2/3Ca1/3MnO3 (LCMO) on
superconducting (SC) (100)YBa2Cu3O7-delta (YBCO) reveal long-range penetration
of superconducting order into the LCMO. This anomalous proximity effect
manifests itself in the tunneling spectra measured on the LCMO layer as gaps
and zero bias conductance peaks. Remarkably, these proximity-induced spectral
features were observed for bilayers with LCMO thickness of up to 30 nm, an
order of magnitude larger than the expected ferromagnetic coherence length in
LCMO. We argue that this long-range proximity effect can be accounted for by
the formation of spin triplet pairing at the LCMO side of the bilayer due to
magnetic inhomogeneity at the interface or at domain walls. Possible symmetries
of the induced order parameter are discussed.
