半導体スピントロニクス
キーワード:スピントロニクス; 半導体デバイス; 結晶成長
2021.08~2023.03.
山下 尚人(やました なおと) | データ更新日:2023.06.19 |
主な研究テーマ
研究業績
主要原著論文
1. | N. Yamashita, R. Mitsuishi, Y. Nakamura, K. Takeda, M. Hori, K. Kamataki, T. Okumura, K. Koga, M. Shiratani, Role of insoluble atoms in the formation of a three-dimensional buffer layer in inverted Stranski–Krastanov mode, J. Mater. Res, 10.1557/s43578-022-00886-7, 1-8, 2023.01, [URL]. |
2. | N. Yamashita, E. Shigematsu, S. Honda, R. Ohshima, M. Shiraishi, Y. Ando, Realization of efficient tuning of the Fermi level in iron-based ferrimagnetic alloys, Physical Review Materials, 10.1103/physrevmaterials.6.104405, 6, 10, 104405, 2022.10, The Stoner criterion allows only three single elements possessing room-temperature (RT) ferromagnetism: cobalt (Co), nickel (Ni), and iron (Fe). Although these three elements have played central roles in magnetism-based materials, their large work function (4.5∼5.2eV) is becoming a non-negligible obstacle for realization of spin devices using nonmetallic materials with finite energy gaps, because injection of electron spins into these nonmetallic materials is strongly hampered due to the large Schottky barrier height. Hence, a novel ferromagnetic or ferrimagnetic material simultaneously possessing RT ferromagnetism or ferrimagnetism and high Fermi energy is strongly required. Here, we show that an Fe-based alloy, iron-gadolinium (FeGd), allows circumvention of the obstacle. Surprisingly, only 20% of Gd incorporation in Fe dramatically modulates the Fermi energy from -4.8 to -3.0 eV, which is the largest modulation in all metallic alloys reported thus far. The coexistence of ferrimagnetism and nonzero spin polarization at RT of FeGd supports its abundant potential for future applications in low-carrier-density materials such as monolayer, organic, and nondegenerate inorganic semiconductors.. |
3. | D. Takahashi, N. Yamashita, D. Yamashita, T. Okumura, K. Kamataki, K. Koga, M. Shiratani, N. Itagaki, Epitaxial Growth of Zn1-xMgxO Films on Sapphire Substrates via Inverted Stranski-Krastanov Mode Using Magnetron Sputtering, MRS Adv., 10.1557/s43580-022-00234-1, 2022.02, [URL]. |
4. | Yuta Nakamura, Naoto Yamashita, Kunihiro Kamataki, Takamasa Okumura, Kazunori Koga, Masaharu Shiratani, Naho Itagaki, Growth of Single-Crystalline ZnO Films on 18%-Lattice-Mismatched Sapphire Substrates Using Buffer Layers with Three-Dimensional Islands, Crystal Growth & Design, 10.1021/acs.cgd.2c00145, 22, 6, 3770-3777, 2022.06. |
5. | Naoto Yamashita, Yuichiro Ando, Hayato Koike, Shinji Miwa, Yoshishige Suzuki, Masashi Shiraishi, Thermally Generated Spin Signals in a Nondegenerate Silicon Spin Valve, Physical Review Applied, 10.1103/physrevapplied.9.054002, 9, 5, 054002, 2018.05. |
主要学会発表等
学会活動
その他の研究活動
受賞
応用物理学会第5回英語講演奨励賞, 応用物理学会スピントロニクス分科会, 2016.09.
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九大関連コンテンツ
QIR 九州大学学術情報リポジトリ システム情報科学研究院
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