Creation of topological phases and simulation of electronic states using atom manipulation technique

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K22135
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 29:Applied condensed matter physics and related fields
• Research Institution: Institute of Physical and Chemical Research
• Principal Investigator: Nantoh Masashi 国立研究開発法人理化学研究所, 開拓研究本部, 専任研究員 (90300889)
• Project Period (FY): 2019-06-28 – 2022-03-31
• Keywords: 原子操作 / 低温STM / 分子グラフェン / トンネル電子分光 / エッジ状態 / 超伝導ギャップ / マヨラナフェルミオン / Yu-Shiba-Rusinov状態

Outline of Final Research Achievements

We performed atom manipulation experiments using a low-temperature scanning tunneling microscope to fabricate artificial topological phases. The molecular graphene was formed on the CO/Cu(111) system, and tunneling spectra were measured at the positions corresponding to the armchair edge and the zigzag edge, which however did not show the rational difference reflecting the edge states. Then, we tried to fabricate the one-dimensional structure of Fe atoms on Pb(110) surface to create Majorana bound states. On the surface atomically resolved by the LT-STM where the measured tunneling spectra exhibited the superconducting energy gap, we succeeded in manipulation of isolated Fe atoms. However, it was found that the Fe-Pb coupling is very strong and dimers are easily formed by the manipulation, which makes the experiment difficult. We continue the experiments to search for ideal systems for the purpose.

Free Research Field

固体物理

Academic Significance and Societal Importance of the Research Achievements

走査型トンネル顕微鏡を用いて極低温・超高真空という環境下で、固体の表面において原子や分子を一つ一つ動かして、一次元や二次元の構造を人工的に作り出す原子操作の実験は、30年の歴史がありながらその難易度の高さから未だ十分には行なわれていない。特にこの手法を物質探索に用い、ターゲットに近年発見されたばかりのトポロジカル物質を含める試みは殆ど手付かずであることから、成功すれば物質科学に新たな分野を切り開く可能性があり、社会に与えるインパクトも大きいと考えられる。