Spin-polarized tunneling in MgO-based tunnel junctions with superconducting electrodes

Abstract

We prepared magnetic tunnel junctions with one ferromagnetic and one superconducting Al–Si electrode. Pure cobalt electrodes were compared with a Co–Fe–B alloy and the Heusler compound Co[subscript 2]FeAl. The polarization of the tunneling electrons was determined using the Maki–Fulde model and is discussed along with the spin–orbit scattering and the total pair-breaking parameters. The junctions were post-annealed at different temperatures to investigate the symmetry filtering mechanism responsible for the giant tunneling magnetoresistance ratios in Co–Fe–B/MgO/Co–Fe–B junctions.