Andreev reflection: A new means to determine the spin polarization of ferromagnetic materials

We have developed a simple method to measure the transport spin polarizatio n of ferromagnetic materials. This technique relies on the fact that the An dreev reflection process at the interface between a superconductive and nor mal is influenced by the spin polarization P of the normal metal. In a very short time we have been able to measure the spin polarization of several m etals: NixFe1-x, Ni, Co, Fe, NiMnSb, La0.7Sr0.3MnO3, and CrO2, whose spin p olarization ranges from 35% to 90%. Our results compare well with other met hods for measuring P. (C) 1999 American Institute of Physics. [S0021-8979(9 9)25208-5].