Enhancement of spin-orbit torque efficiency by tailoring interfacial spin-orbit coupling in Pt-based magnetic multilayers |
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Affiliation: | 1.National Laboratory of Solid State Microstructures, School of Physics and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China;2.New Energy Technology Engineering Laboratory of Jiangsu Provence and School of Science, Nanjing University of Posts and Telecommunications, Nanjing 210023, China;3.Centre for Integrated Spintronic Devices, School of Electronics and Information, Hangzhou Dianzi University, Hangzhou 310018, China |
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Abstract: | We study inserting Co layer thickness-dependent spin transport and spin-orbit torques (SOTs) in the Pt/Co/Py trilayers by spin-torque ferromagnetic resonance. The interfacial perpendicular magnetic anisotropy (IPMA) energy density ($K_{rm s}= 2.7 $ erg/cm$^{2}$, 1 erg = 10$^{-7}$ J), which is dominated by interfacial spin-orbit coupling (ISOC) in the Pt/Co interface, total effective spin-mixing conductance $(G_{mathrm{eff,tot}}^{mathrm{uparrow downarrow }}=mathrm{0.42times }{10}^{15} mathrm{Omega }^{-1}cdotmathrm{m}^{-2}$) and two-magnon scattering ($beta_{mathrm{TMS}}= 0.46 {mathrm{nm}}^{2}$) are first characterized, and the damping-like torque ($xi_{mathrm{DL}}= 0.103$) and field-like torque ($xi _{mathrm{FL}}=-0.017$) efficiencies are also calculated quantitatively by varying the thickness of the inserting Co layer. The significant enhancement of $xi_{mathrm{DL}}$ and $xi_{mathrm{FL}}$ in Pt/Co/Py than Pt/Py bilayer system originates from the interfacial Rashba-Edelstein effect due to the strong ISOC between Co-3d and Pt-5d orbitals at the Pt/Co interface. Additionally, we find a considerable out-of-plane spin polarization SOT, which is ascribed to the spin anomalous Hall effect and possible spin precession effect due to IPMA-induced perpendicular magnetization at the Pt/Co interface. Our results demonstrate that the ISOC of the Pt/Co interface plays a vital role in spin transport and SOTs-generation. Our finds offer an alternative approach to improve the conventional SOTs efficiencies and generate unconventional SOTs with out-of-plane spin polarization to develop low power Pt-based spintronic via tailoring the Pt/FM interface. |
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Keywords: | spin-orbit torque interfacial Rashba-Edelstein effect spin-torque efficiency spin-torque ferromagnetic resonance |
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