Novel spin filter function using graphene nanoribbon

2020 Fiscal Year Final Research Report

• Project/Area Number: 19K21850
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 13:Condensed matter physics and related fields
• Research Institution: Osaka University
• Principal Investigator: Niimi Yasuhiro 大阪大学, 理学研究科, 准教授 (00574617)
• Project Period (FY): 2019-06-28 – 2021-03-31
• Keywords: グラフェン / ナノリボン / トポロジー / スピンフィルタ / スピントロニクス

Outline of Final Research Achievements

In this work, we aimed to develop spin filter function using one-dimensional graphene chain, i.e., graphene nanoribbon. If the edges have zigzag shape, spin polarized states are realized at the edges. In such a case, spin filter function can be added by doping holes in graphene and applying a tiny magnetic field. For this purpose, we tried to fabricate graphene nanoribbons in between hexagonal defects which can be formed by irradiating oxygen and hydrogen plasma. However, it turned out that a high-resolution atomic force microscopy was needed to confirm the edge shape. Thus, we performed magnetotransport measurements for the irradiated graphene sample. A clear weak localization peak was observed near zero magnetic field. This peak increases with increasing the irradiation time.
In future, we will try to make graphene nanoribbons with a width of less than 100 nm and fabricate spin filter devices where spin states can be selectively tuned by gating.

Free Research Field

低温スピン物性

Academic Significance and Societal Importance of the Research Achievements

今後は幅100 nm以下のグラフェンナノリボンの作製、さらには電界効果を用いて、スピンフィルタ機能を付与したデバイスの作製に挑戦する。同様の機能は「電界効果スピントランジスタ」としてダッタとダスが提案しているが、未だ実現できてない。グラフェンナノリボンでスピンフィルタを実現できれば、1次元フラットバンド強磁性という未だ実証されていない物性物理の基本問題に答えるだけでなく、スピン抽出という新機能をスピントロニクスデバイスに付与できる。