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

• Published in: Chinese physics B Vol. 31; no. 9; pp. 97504 - 165
• Main Authors: Wang, Wenqiang, Zhu, Gengkuan, Zhou, Kaiyuan, Zhan, Xiang, Tao, Zui, Fu, Qingwei, Liang, Like, Li, Zishuang, Chen, Lina, Yan, Chunjie, Li, Haotian, Zhou, Tiejun, Liu, Ronghua
• Format: Journal Article
• Language: English
• Published: Chinese Physical Society and IOP Publishing Ltd 01.09.2022; National Laboratory of Solid State Microstructures,School of Physics and Collaborative Innovation Center of Advanced Microstructures,Nanjing University,Nanjing 210093,China%National Laboratory of Solid State Microstructures,School of Physics and Collaborative Innovation Center of Advanced Microstructures,Nanjing University,Nanjing 210093,China; New Energy Technology Engineering Laboratory of Jiangsu Provence and School of Science,Nanjing University of Posts and Telecommunications,Nanjing 210023,China%Centre for Integrated Spintronic Devices,School of Electronics and Information,Hangzhou Dianzi University,Hangzhou 310018,China
• Subjects: interfacial Rashba-Edelstein effect; spin-orbit torque; spin-torque efficiency; spin-torque ferromagnetic resonance; spin-orbit torque; interfacial Rashba-Edelstein effect; spin-torque efficiency; spin-torque ferro-magnetic resonance
• ISSN: 1674-1056; 2058-3834
• DOI: 10.1088/1674-1056/ac76aa

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 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 eff , tot ↑ ↓ = 0 . 42 × 10 15 Ω − 1 ⋅ m − 2 ) and two-magnon scattering ( β TMS = 0.46 nm 2 ) are first characterized, and the damping-like torque ( ξ DL = 0.103) and field-like torque ( ξ FL = –0.017) efficiencies are also calculated quantitatively by varying the thickness of the inserting Co layer. The significant enhancement of ξ DL and ξ 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.