SPIN POLARIZED TUNNELING IN RARE-EARTH FERROMAGNETS

We have measured the spin polarization of tunneling electrons in junctions between thin Al films and films of the heavy rare earth metals Gd to Yb. These metals are known from other experiments to have positively polarized conduction electrons. All polarizations measured by tunneling are positive and are approximately proportional to the part of the saturation magnetic moment per atom attributed to the conduction electrons.