Large voltage effect in 3-fold axis oriented magnetic tunnel junctions with corundum oxides

Research Project

Project/Area Number	18H05947
Research Category	Grant-in-Aid for Research Activity Start-up
Allocation Type	Single-year Grants
Review Section	0402:Nano/micro science, applied condensed matter physics, applied physics and engineering, and related fields
Research Institution	Tohoku University
Principal Investigator	Ichinose Tomohiro 東北大学, 材料科学高等研究所, 学術研究員 (20826953)
Project Period (FY)	2018-08-24 – 2019-03-31
Project Status	Completed (Fiscal Year 2018)
Budget Amount *help	¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000) Fiscal Year 2018: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
Keywords	スピントロニクス / コランダム酸化物 / 磁気トンネル接合 / トンネル磁気抵抗効果 / コランダム
Outline of Final Research Achievements	Large voltage effect on the magnetic properties is the crucial issue to reduce the energy consumption in the magnetic random-access memories. The use of large voltage is the one of the routes to increase the voltage effect on the magnetic properties. In this work, magnetic tunnel junctions using corundum oxide expected to be high dielectric breakdown strength material were prepared, and its transport properties under the high voltage were investigated. Cr2O3 with corundum structure crystallized with (001) orientation even it was deposited at room temperature. Magnetic tunnel junctions with Cr2O3 barrier oxidized by using oxygen plasma showed the high dielectric breakdown strength of ~ 5 MV/cm.
Academic Significance and Societal Importance of the Research Achievements	室温で成膜した場合においてもCr2O3が(001)配向することを見出し, 3回対称軸方向に配向した磁気トンネル接合の作製について端緒を開いた. これにより立方晶系(001)配向以外の対称性を有する材料に対して可能性が開け, 材料選択の幅が拡がると考えられる. また,電気磁気効果を示す反強磁性体であるCr2O3を障壁層に用いることで磁気トンネル接合に新奇な機能を付与できる可能性がある.