Equal-spin Andreev reflection and long-range coherent transport in high-temperature superconductor/half-metallic ferromagnet junctions

The penetration of a superconducting current from a superconductor into a half-metallic ferromagnet is usually forbidden. Resonances in the conductance spectra of superconductor/half-metal heterostructures suggest this restriction is lifted by the occurrence of unconventional equal-spin Andreev reflection.