2020 Fiscal Year Research-status Report
超高密度メモリデバイスを実現する反強磁性異方性トンネル接合素子の創製
| Project/Area Number |
20K04569
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| Research Institution | National Institute for Materials Science |
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Principal Investigator |
温 振超 国立研究開発法人物質・材料研究機構, 磁性・スピントロニクス材料研究拠点, 主任研究員 (40784773)
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| Project Period (FY) |
2020-04-01 – 2023-03-31
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| Keywords | Antiferromagnet / Tunnel junctions |
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| Outline of Annual Research Achievements |
In the first year of this project, we fabricated epitaxial antiferromagnetic (AFM) FeRh thin films on MgO(001) substrate with the optimization of deposition conditions. A sharp phase transition from ferromagnetic to AFM was observed with temperature and magnetic field. Room-temperature bulk AFM phase of FeRh was achieved. We further fabricated antiferromagnetic tunnel junction (AFMTJ) stacks with the core structure of FeRh/MgO/CoFe. Interestingly, we found that the sign of magnetoresistance changes with the directions of applied bias voltages, i.e., a bipolar tunneling magnetoresistance (TMR) was achieved. We further found that the bipolar TMR effect originates from the unique density of states of the ferromagnetic FeRh at the interface.
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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 optimized the deposition condition of antiferromagnetic FeRh thin films and have fabricated antiferromagnetic tunnel junctions with the core structure of FeRh/MgO/CoFe, which follows our research plans. Therefore, the project is progressing rather smoothly.
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| Strategy for Future Research Activity |
In order to accelerate the project, new characterizations and more optimizations for the antiferromagnetic (AFM) materials are strongly required, which is also important for establishing new research aspects. Therefore, we plan to design and engineer new AFM materials and related structures, e.g. colinear AFM RuO2, and noncolinear AFM IrMn, and to start new structural characterizations for optimizing the AFM materials, e.g. XMLD measurements.
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