Comparison between spin-orbit torques measured by domain-wall motions and harmonic measurements

Here we report the comparison of the spin torque efficiencies measured by three different experimental schemes for Pt/Co/X stacks with material X (= Pt, Ta, Ti, Al, Au, Pd, and Ru. 7 materials). The first two spin torque efficiencies εDW(1) and εDW(2) are quantified by the measurement of spin-torque-induced effective field for domain-wall depinning and creeping motions, respectively. The last one—longitudinal spin torque efficiency εL—is measured by harmonic signal measurement of the magnetization rotation with uniform magnetization configuration. The results confirm that, for all measured Pt/Co/X stacks, εDW(1) and εDW(2) are exactly consistent to each other and these two efficiencies are roughly proportional to εL with proportionality constant π/2, which comes from the integration over the domain-wall configuration.