Spin polarization of tunneling current from ferromagnet/Al₂O₃ interfaces using copper-doped aluminum superconducting films

Superconducting Cu-doped Al films sputtered at room temperature (RT) show improved characteristics for superconductor-insulator-ferromagnet spin-polarization measurements as compared to dirty Al films evaporated at 77 K. Detailed analysis including temperature, depairing and spin-orbit effects reveal spin-polarization values for a large variety of ferromagnetic transition-metal alloys. The high-spin polarization for these RT-sputtered junctions is consistent with large tunnel magnetoresistance values observed in similarly sputtered magnetic tunnel junctions. © 2000 American Institute of Physics.