Spin-polarized tunneling in La0.67Sr0.33MnO3

We have developed the ability to grow reproducible La0.67Sr0.33MnO3/SrTiO3/Al tunnel junctions with high quality gap characteristics for spin-polarization measurements. A YBa2Cu3O7 counterelectrode was required to prevent current crowding. In order to fit our data, we have numerically solved Maki's equations which include the effects of orbital depairing, the Zeeman splitting of the spin states, and spin-orbit scattering. We consistently measure P=+72%, for a variety of deposition conditions. (C) 2000 American Institute of Physics. [S0003-6951(00)00307-7].