Improving perpendicular magnetic anisotropy of Fe/MgO and its voltage controllability by introducing nonmagnetic elements

• Project/Area Number: 20K15158
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 29010:Applied physical properties-related
• Research Institution: The University of Tokyo
• Principal Investigator: Sakamoto Shoya 東京大学, 物性研究所, 助教 (50868114)
• Project Period (FY): 2020-04-01 – 2022-03-31
• Project Status: Completed (Fiscal Year 2021)
• Budget Amount: ¥4,160,000 (Direct Cost: ¥3,200,000、Indirect Cost: ¥960,000); Fiscal Year 2021: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000); Fiscal Year 2020: ¥2,340,000 (Direct Cost: ¥1,800,000、Indirect Cost: ¥540,000)
• Keywords: スピントロニクス / 磁気異方性 / 磁気異方性制御 / 放射光分光 / 磁性体

Outline of Research at the Start

電子の電荷に加えスピンを利用し電子デバイスの性能向上を図るスピントロニクス分野において、鉄と酸化マグネシウムからなる薄膜デバイスは非常に有望視されている。本研究では、電圧によって磁性を制御する、新しい超低消費電力の情報書き込み方式に着目する。この新しい方式では、鉄の磁性の電圧制御効率が低いことが課題であるが、これまでにプラチナなどの重い元素を導入することでその効率が向上することがわかっている。本研究では、重い元素でなく、軽い元素を導入することによる性能向上を目指す。

Outline of Final Research Achievements

In this project, we aimed to improve the magnetic anisotropy of Fe/MgO-based systems and its sensitivity to voltage application by introducing nonmagnetic metal elements. First, we examined how electrons behave at the Fe/MgO interface by performing synchrotron spectroscopy measurements and obtained new insights into the origin of magnetic anisotropy in Fe/MgO systems. Next, we doped V or Al in Fe/MgO to modify the position of the Fermi level or the electronic structure. We find that V doping, which introduce electrons to the system, can increase the sensitivity of magnetic anisotropy to the voltage application.

Academic Significance and Societal Importance of the Research Achievements

Fe/MgOをベースとした薄膜は、次世代磁気メモリにおいて最も重要な要素であり、FeとMgOの界面が生み出す磁気異方性とその電圧変調効率を向上することが課題となっている。本研究成果は、Fe/MgOにおける磁気異方性の起源に関する新しい知見を与えただけでなく、従来までの重元素を導入する以外の方法で性能向上が可能であることを示した点で意義があり、今後の研究の展開が期待される。

Research Products

• [Int'l Joint Research] University of York(英国)
• [Journal Article] Electron Correlation Enhances Orbital Polarization at a Ferromagnetic Metal/Insulator Interface: Depth-Resolved X-ray Magnetic Circular Dichroism and First-Principles Study (2022)
  • Author(s): Shoya Sakamoto, Masahito Tsujikawa, Masafumi Shirai, Kenta Amemiya, and Shinji Miwa
  • Journal Title: ACS Applied Electronic Materials Volume: 4 Issue: 4 Pages: 1794-1799
  • DOI: 10.1021/acsaelm.2c00049
  • Peer Reviewed
• [Journal Article] Control of perpendicular magnetic anisotropy at the Fe/MgO interface by phthalocyanine insertion (2022)
  • Author(s): Shoya Sakamoto, Edward Jackson, Takeshi Kawabe, Takuya Tsukahara, Yoshinori Kotani, Kentaro Toyoki, Emi Minamitani, Yoshio Miura, Tetsuya Nakamura, Atsufumi Hirohata, and Shinji Miwa
  • Journal Title: Physical Review B Volume: －
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Influence of epitaxial strain on the perpendicular magnetic anisotropy of Fe/MgO systems (2021)
  • Author(s): Masanobu Shiga, Shoya Sakamoto, Takaya Tsujikawa, Ryoya Ando, Kenta Amemiya, and Shinji Miwa
  • Journal Title: Physical Review B Volume: 104 Issue: 14
  • DOI: 10.1103/physrevb.104.l140406
  • Peer Reviewed
• [Journal Article] Observation of spontaneous x-ray magnetic circular dichroism in a chiral antiferromagnet (2021)
  • Author(s): Shoya Sakamoto, Tomoya Higo, Masanobu Shiga, Kenta Amemiya, Satoru Nakatsuji, and Shinji Miwa
  • Journal Title: Physical Review B Volume: 104 Issue: 13 Pages: 134431-134431
  • DOI: 10.1103/physrevb.104.134431
  • Peer Reviewed
• [Journal Article] Low Gilbert damping in epitaxial thin films of nodal-line semimetal D03-Fe3Ga (2021)
  • Author(s): Shoya Sakamoto, Tomoya Higo, Shingo Tamaru, Hitoshi Kubota, Kay Yakushiji, Satoru Nakatsuji, and Shinji Miwa
  • Journal Title: Physical Review B Volume: 103 Issue: 16 Pages: 165122-165122
  • DOI: 10.1103/physrevb.103.165122
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Presentation] Observation of spontaneous x-ray magnetic circular dichroism in the antiferromagnetic Mn3Sn thin film (2022)
  • Author(s): Shoya Sakamoto, Tomoya Higo, Masanobu Shiga, Kenta Amemiya, Satoru Nakatsuji, and Shinji Miwa
  • Organizer: 2022年 第69回 応用物理学会春季学術講演会
• [Presentation] Spontaneous x-ray magnetic circular dichroism in the antiferromagnetic Mn3Sn epitaxial thin film (2022)
  • Author(s): Shoya Sakamoto, Tomoya Higo, Masanobu Shiga, Kenta Amemiya, Satoru Nakatsuji, and Shinji Miwa
  • Organizer: 24th International Colloquium on Magnetic Films and Surfaces (ICMFS-2022)
  • Int'l Joint Research
• [Presentation] Depth profile of the Fe spin and orbital magnetic moments in a V/Fe/MgO trilayer revealed by depth-resolved x-ray magnetic circular dichroism (2021)
  • Author(s): Shoya Sakamoto, Masahito Tsujikawa, Masafumi Shirai, Kenta Amemiya, and Shinji Miwa
  • Organizer: 2021年 第68回 応用物理学会 春季学術講演会