Andreev States in Clean Ferromagnetic Layers

We study the superconducting proximity effect in clean ferromagnetic layers with rough boundaries. We obtain a general formula for the density of states at all energies which is completely specified by the length distribution of the classical trajectories inside the ferromagnetic layer. Phase shifting by the ferromagnetic exchange field results in many interesting effects, including spin splitting of the subgap density of states, a zero energy Andreev peak, resonant transmission peaks above the gap, and oscillations of the density of states as a function of the layer thickness. We show that our results agree quantitatively with recent experiments.