Spin-orbit torques (SOTs) allow controlling the magnetization of diverse classes of magnetic multilayers and devices. The mechanism utilizes spin-orbit interactions such as spin Hall effect in heavy metals and/or Rashba effect at ferromagnetic/heavy-metal interface with broken inversion symmetry. The SOTs have damping-like (HDL) and field-like (HFL) effective field components. In this talk, we will present the mechanism of spin-transport in ultrathin magnetic multilayer whose thicknesses span across the characteristic spin-dephasing length, and how it results in HDL and HFL nearby the crossing point of this specific length. To this aim, we have quantified SOTs in a series of samples Pt 8|Co x|Al 1.4|Pt 3 with x = 0.55, 0.7, 0.9, 1.2, 1.4 nm. Our experiments demonstrate the presence of very large field-like torque arising from Co|Al interface for Co thickness smaller than spin-dephasing length. The results suggest the contribution of additional mechanisms of spin-current generation.
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