A superconducting point contact is used to determine the spin polarization at the Fermi energy of several metals. Because the process of supercurrent conversion at a superconductor-metal interface (Andreev reflection) is limited by the minority spin population near the Fermi surface, the differential conductance of the point contact can reveal the spin polarization of the metal. This technique has been applied to a variety of metals where the spin polarization ranges from 35 to 90 percent: Ni0.8Fe0.2, Ni, Co, Fe, NiMnSb, La0.7Sr0.3MnO3, and CrO2.

We have developed a simple method to measure the transport spin polarization of ferromagnetic materials. This technique relies on the fact that the Andreev reflection process at the interface between a superconductive and normal 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 metals: NixFe1−x, Ni, Co, Fe, NiMnSb, La0.7Sr0.3MnO3, and CrO2, whose spin polarization ranges from 35% to 90%. Our results compare well with other methods for measuring P.