Andreev Reflection in Ballistic Superconductor-Ferromagnet Contacts

摘要

On the basis of Eilenberger-type equations of superconductivity for metals with exchange-split conduction band we derive an original expression for the Andreev conductance of superconductor-ferromagnet point contacts. We give particular formulas for different relations between Fermi momenta of contacting metals, and calculate the Andreev conductance as a function of exchange splitting of the ferromagnet conduction band. From comparison with experimental data on point contact Andreev reflection spectroscopy we estimate the conduction band spin polarization for a series of ferromagnets in contact with superconductors.