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Chin. Phys. B, 2022, Vol. 31(9): 097504    DOI: 10.1088/1674-1056/ac76aa

Enhancement of spin-orbit torque efficiency by tailoring interfacial spin-orbit coupling in Pt-based magnetic multilayers

Wenqiang Wang(王文强)1, Gengkuan Zhu(朱耿宽)1, Kaiyuan Zhou(周恺元)1, Xiang Zhan(战翔)1, Zui Tao(陶醉)1, Qingwei Fu(付清为)1, Like Liang(梁力克)1, Zishuang Li(李子爽)1, Lina Chen(陈丽娜)1,2,†, Chunjie Yan(晏春杰)1, Haotian Li(李浩天)1, Tiejun Zhou(周铁军)3,‡, and Ronghua Liu(刘荣华)1,§
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
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 $(G_{\mathrm{eff,tot}}^{\mathrm{\uparrow \downarrow }}=\mathrm{0.42\times }{10}^{15} \mathrm{\Omega }^{-1}\cdot\mathrm{m}^{-2}$) 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.
Keywords:  spin-orbit torque      interfacial Rashba-Edelstein effect      spin-torque efficiency      spin-torque ferromagnetic resonance  
Received:  06 April 2022      Revised:  28 May 2022      Accepted manuscript online:  08 June 2022
PACS:  75.70.Tj (Spin-orbit effects)  
  75.70.-i (Magnetic properties of thin films, surfaces, and interfaces)  
  75.76.+j (Spin transport effects)  
  75.78.-n (Magnetization dynamics)  
Fund: Project supported by the National Natural Science Foundation of China (Grant Nos. 11774150, 12074178, 11874135, and 12004171), the Applied Basic Research Programs of the Science and Technology Commission Foundation of Jiangsu Province, China (Grant No. BK20200309), the Open Research Fund of Jiangsu Provincial Key Laboratory for Nanotechnology, Key Research and Development Program of Zhejiang Province, China (Grant No. 2021C01039), and the Scientific Foundation of Nanjing University of Posts and Telecommunications (Grant No. NY220164).
Corresponding Authors:  Lina Chen, Tiejun Zhou, Ronghua Liu     E-mail:;;

Cite this article: 

Wenqiang Wang(王文强), Gengkuan Zhu(朱耿宽), Kaiyuan Zhou(周恺元), Xiang Zhan(战翔), Zui Tao(陶醉), Qingwei Fu(付清为), Like Liang(梁力克), Zishuang Li(李子爽), Lina Chen(陈丽娜), Chunjie Yan(晏春杰), Haotian Li(李浩天), Tiejun Zhou(周铁军), and Ronghua Liu(刘荣华) Enhancement of spin-orbit torque efficiency by tailoring interfacial spin-orbit coupling in Pt-based magnetic multilayers 2022 Chin. Phys. B 31 097504

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