Correlation between magnetism and spin-dependent transport in CoFeB alloys

We report a correlation between the spin polarization of the tunneling electrons (TSP) and the magnetic moment of amorphous CoFeB alloys. Such a correlation is surprising since the TSP involves s-like electrons close to the Fermi level (EF), while the magnetic moment mainly arises due to all d-electrons below EF. We show that probing the s and d-bands individually provides clear and crucial evidence for such a correlation to exist through s-d hybridization, and demonstrate the tuneability of the electronic and magnetic properties of CoFeB alloys.Comment: Accepted for publication in Physical Review Letters. Letter (4 pages) and Supplementary material (4 pages

Sign reversal of spin polarization in Co/Ru/Al2O3/Co magnetic tunnel junctions

Utilizing ultrathin Ru interfacial layers in Co/Al2O3/Co tunnel junctions, we demonstrate that not only does the tunnel magnetoresistance decrease strongly as the Ru thickness increases as found for Cu or Cr interlayers, in contrast, even the sign of the apparent tunneling spin polarization may be changed. Further, the magnitude and sign of the apparent polarization is strongly dependent on applied voltage. The results are explained by a strong density-of-states modification at the (interdiffused) Co/Ru interface, consistent with theoretical calculations and experiments on Co/Ru metallic multilayers and Co-Ru alloys

Asymmetric Pt/Co/Pt-stack induced sign-control of current-induced magnetic domain-wall creep

We report experimentally obtained magnetic domain wall (DW) velocities of current-assisted field-driven DW creep in perpendicularly magnetized Pt/Co/Pt. We have intentionally introduced an asymmetry in the stacks by using different thicknesses of the two Pt layers sandwiching the Co layer. Thereby, it is tested whether conflicting current-induced domain wall motion (CI-DWM) results may be intrinsically related to the basic layout and growth. We sketch a scenario which could be at the basis of contradicting reports in literature where the direction of CI-DWM conflicts with spin-torque-transfer theory, allowing the sign of the current-induced effect on DW motion to be tuned