Quantum spin fluctuations as a source of long-range proximity effects in diffusive ferromagnet-superconductor structures

We show that quantum spin fluctuations in inhomogeneous ferromagnets drastically affect the Andreev reflection of electrons and holes at a ferromagnet-superconductor interface. As a result, a strong long-range proximity effect appears, associated with electron-hole spin-triplet correlations and persisting on a length scale typical for non-magnetic materials, but anomalously large for ferromagnets.