Supercurrents in half-metallic ferromagnetic La0.7Ca0.3MnO3

Conventional singlet Cooper pairs from a superconductor (S) are short-ranged in a ferromagnet (F) because the magnetic exchange field in the latter acts differently on the antiparallel electrons which form the pair. This is not the case for parallel spin triplet pairs and long-range proximity effects have now been found in a variety of systems. A triplet supercurrent should be 100% spin-polarised in a half-metallic ferromagnet: here we show that inhomogeneous magnetism in all-oxide epitaxial S/half-metal/S heterostructures can generate the long-range supercurrents necessary to develop superconducting spin electronics.