New Method to Study the Electron Spin Polarization at the Fermi Level of a Ferromagnetic Metal

An applied magnetic field shifts the energy levels of spin-up and spin-down electrons in opposite directions. In a ferromagnetic metal, the resulting redistribution of the electrons over the spin bands gives rise to a shift of the Fermi level that is dependent on the degree of spin polarization of the electrons at the Fermi energy. The shift has been measured as a magnetic field dependence of the contact potential of polycrystalline Ni films. The influences of interface effects and of effects due to magnetostriction prevent a quantitative analysis of the results so far.