2021 Fiscal Year Annual Research Report
Deciphering spin-orbit torque in magnetic single layers: Towards spin-torque devices with extended scalability
| Project/Area Number |
20K15156
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| Research Institution | Tohoku University |
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Principal Investigator |
LAU Yongchang 東北大学, 金属材料研究所, 特任助教 (60795764)
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| Project Period (FY) |
2020-04-01 – 2022-03-31
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| Keywords | Compensated ferrimagnet / Spin-orbit torque / Spin-orbitronics / Spin caloritronics / Anomalous Nernst effect |
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| Outline of Annual Research Achievements |
The growth of a new ternary inverse Heusler compound Mn-Ru-Al (MRA) epitaxial films on MgO(001) substrates is demonstrated by magnetron co-sputtering Mn55Al45 and Ru targets. The highly tunable MRA resembles compensated ferrimagnetic Mn2RuxGa (MRG). Ga atoms of MRG are replaced by the isovalent Al in MRA, leading to a smaller lattice parameter of MRA. By varying the Ru concentration, magnetic compensation at room temperature is achieved in MRA. However, the growth of MRG/MRA on zinc-blende-structured GaAs or Fe-doped InP substrates by sputtering has proved to be rather challenging. This is mostly hindered by the severe interdifussion at the substrate/film interface. A suitable seed layer should be developed to overcome this limitation and facilitate the quantification of single-layer spin-orbit torques in such materials.
We have also performed preliminary measurements to explore the potential of using MRG as a spin Hall spin current source in MRG/Ti/Py heterostructures. The spin Hall angle of MRG is quantified using spin-torque ferromagnetic resonance technique and we confirmed that the change-spin conversion in MRG is independent of the magnetization direction and is invariant across the magnetic compensation.
We have also investigated the spin-orbit torque in NiFe single layer and the change-spin conversion in Pt-Al and Co-Si alloys. Overall, in FY2021, this project leads to 3 publications and 1 oral presentation in the IEEE INTERMAG conference.
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