Enhancement of the spin–orbit torque efficiency in W/Cu/CoFeB heterostructures via interface engineering

Journal Article · Sun Aug 23 20:00:00 EDT 2020 · Applied Physics Letters

DOI: https://doi.org/10.1063/5.0015557 · OSTI ID:1802452

Yang, Pei ^[1]; Shao, Qiming  ^[2]; Yu, Guoqiang ^[3]; He, Congli ^[3]; Wong, Kin  ^[4]; Lu, Xianyang  ^[5]; Zhang, Junran  ^[5]; Liu, Bo ^[6]; Meng, Hao ^[6]; He, Liang  ^[5]; Wang, Kang L. ^[4]; Xu, Yongbing ^[7]

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1. Nanjing Univ. (China); Univ. of California, Los Angeles, CA (United States); OSTI
2. Univ. of California, Los Angeles, CA (United States); The Hong Kong University of Science and Technology (China)
3. Univ. of California, Los Angeles, CA (United States); Beijing Normal University (China)
4. Univ. of California, Los Angeles, CA (United States)
5. Nanjing Univ. (China)
6. Key Laboratory of Spintronics Materials, Devices and Systems of Zhejiang Province, Zhejiang Province, China (Asia)
7. Nanjing Univ. (China); Univ. of York (United Kingdom)

Here, the spin-torque ferromagnetic resonance signal and the spin Hall magnetoresistance induced by the spin Hall effect of W/Cu/CoFeB heterostructures with different Cu layer thicknesses (t_Cu) have been systemically studied. The effective spin mixing conductance $$g^{↑↓}_{eff}$$, the interfacial spin transparency T, and the real spin–orbit torque efficiency ${\left(\frac{J_{\mathrm{s}}}{J_{\mathrm{c}}}\right)}_{\mathrm{real}}$show a significant increase compared to the W/CoFeB heterostructure. ${\left(\frac{J_{\mathrm{s}}}{J_{\mathrm{c}}}\right)}_{\mathrm{real}}$reaches its maximum of ~0.54, increased up to ~50% at the optimized tCu ~ 0.52 nm according to our theoretical prediction. More importantly, the intrinsic spin Hall angle of W, $$θ^{int}_{SH}$$ ~ 0.79 ± 0.20, has also been obtained after the correction of the inverse spin Hall effect and T. This suggests that the Cu insertion improves the interface quality and, therefore, assists the spin transport in the heterostructures, which potentially improves the performance of next-generation spintronic devices.

• Research Organization: Univ. of California, Riverside, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• Grant/Contract Number: SC0012670
• OSTI ID: 1802452
• Journal Information: Applied Physics Letters, Journal Name: Applied Physics Letters Journal Issue: 8 Vol. 117; ISSN 0003-6951
• Publisher: American Institute of Physics (AIP)Copyright Statement
• Country of Publication: United States
• Language: English