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The manipulation of magnetization by spin transfer torque is one of the most active field of spintronics due to its use for nonvolatile memory and programmable logic applications. In this work, we use a three-terminal spin-torque oscillator to compare the spin-transfer efficiency of two mechanisms used to induce spin transfer torque: the spin orbit torque (i.e., the torque induced by spin currents produced by spin-orbit scattering in a heavy metal) and the spin filtering torque (i.e., the spin transfer torque obtained via the flow of a spin polarized current through a spin valve (SV) or a magnetic tunnel junction (MTJ)). The device used for this study consists of a SV on top of a Pt wire. The device can be excited either by the spin filtering torque (SFT) or by the spin orbit torque (SOT) depending on whether the current is applied through the SV or through the Pt wire. By varying the Pt width and the dimensions of the SV, we tune the SOT and STT and compare their efficiencies. We show that, for the devices that we study, the SFT is more efficient in terms of current density, whereas the SOT can be more efficient than the SFT in terms of current when the Pt wire is narrower than 700 nm. Finally, we use three control samples (where the Pt wire is replaced by a Cu wire or where the SV is replaced by an MTJ) to discuss the limits of the method.
[1] Jué, Pufall, and Rippard, Journal of Applied Physics 124, 043904 (2018)
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