2022 Fiscal Year Final Research Report
Analysis of Electronic and Positronic States in Long-Period Matched Graphene using Large-Scale First-Principles Band Calculation
Project/Area Number |
20K05454
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Research Category |
Grant-in-Aid for Scientific Research (C)
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Allocation Type | Multi-year Fund |
Section | 一般 |
Review Section |
Basic Section 32020:Functional solid state chemistry-related
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Research Institution | National Institutes for Quantum Science and Technology |
Principal Investigator |
Miyashita Atsumi 国立研究開発法人量子科学技術研究開発機構, 高崎量子応用研究所 放射線高度利用施設部, 主幹研究員 (00354944)
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Project Period (FY) |
2020-04-01 – 2023-03-31
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Keywords | 陽電子 / グラフェン / 計算科学 / 表面 / ポジトロニウム分光 |
Outline of Final Research Achievements |
We performed first-principles band analysis using a 148-atom slab model, which consisted of a (3×1) structure of a horizontal two-unit-cell repetition of Co2FeGa0.5Ge0.5 (CFGG) crystal surface with an aligned (8×2) graphene structure and a 20 Å vacuum layer on the surface. After structural optimization of the model, the distance between the CFGG surface and the graphene layer was determined to be 2.9 Å, corresponding to the van der Waals bonding distance. The electronic density of states for the graphene layer alone was calculated, suggesting that the properties as a spintronics material were retained. To estimate the probability of positronium generation, the product of electron and positron densities was calculated, revealing a spin polarization of approximately 2%, indicating a low spin injection efficiency.
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Free Research Field |
第一原理バンド解析による表面・界面物性評価
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Academic Significance and Societal Importance of the Research Achievements |
本研究課題では、基板物質であるCFGGと長周期で整合するグラフェンのスピン・電子状態を大規模結晶構造に基づく電子・陽電子バンド計算により得ると共に、グラフェンの電子状態解析に極めて有用なポジトロニウム分光のスペクトルを計算し、スピン偏極ポジトロニウム分光実験の詳細な解釈を行っており、実デバイスに利用可能なスピントロニクス材料の評価方法として、大規模結晶構造に基づく電子・陽電子バンド計算が非常に有用な事を示した。
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