2017 Fiscal Year Annual Research Report
Control of spin current and magnetization in chiral antiferromagnetsic and ferrimagnetsic materials
| Project/Area Number |
17F17064
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| Research Institution | The University of Tokyo |
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Principal Investigator |
林 将光 東京大学, 大学院理学系研究科(理学部), 准教授 (70517854)
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| Co-Investigator(Kenkyū-buntansha) |
LAU YONG CHANG 東京大学, 理学(系)研究科(研究院), 外国人特別研究員
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| Project Period (FY) |
2017-04-26 – 2019-03-31
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| Keywords | Chiral magetism / spin current |
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| Outline of Annual Research Achievements |
We have studied the spin current generation and magnetization manipulation in magnetic multilayers. The main research achievements in FY2017 are summarized as followed:
The perpendicular magnetic anisotropy in a 2nm-thick ferrimagnetic MnGa layer was realized using CoGa as a seed layer. Utilizing the spin Hall effect of CoGa, we demonstrated spin-orbit torque induced MnGa magnetization reversal in the same heterostructure. First-principles calculations suggested the intrinsic mechanism was responsible for the spin Hall effect in CoGa. We highlighted the role of d-p hybridized orbitals and the spin-orbit coupling of Co atom in generating the spin current in CoGa.
Antiferromagnetic D019-Mn3Ga films were grown on c-sapphire substrates. Using spin Hall magnetoresistance, we showed that the antiferromagnetic D019-Mn3Ga was a spin current generator with efficiency comparable to that of PtMn. Upon inserting a thin Hf spacer between Mn3Ga and CoFeB, we showed that the spin Hall current generated by Mn3Ga was sufficiently large for reversing the CoFeB magnetization.
We have also explored the spin current generated by a thermal gradient in non-magnetic metals, i.e. the spin Nernst effect. We showed that the spin Nernst angle in W is comparable in magnitude but opposite in sign with its spin Hall angle.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
We have presented our experimental results on spin current generation by antiferromagnet Mn3Ga and paramagnetic CoGa at international conferences. Our paper on spin current generation by heat current (the spin Nernst effect) is published in Science Advances. We thus consider the status of our work is as planned.
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| Strategy for Future Research Activity |
We will continue exploring the interaction between the spin current and the magnetic moments in ferrimagnetic systems. We will focus on Mn2RuxGa system, which is a compensated ferrimagnet with high spin polarization (sample obtained from Trinity College Dublin). Using harmonic Hall technique, we will study the spin-orbit torques generated within the ferrimagnetic layer. We will also explore the possibility of generating spin current in chiral ferri and antiferromagnets using temperature gradients.
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