Theoretical study of atomic and electronic structure of single-element quasicrystalline ultra-thin films

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K05059
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Thin film/Surface and interfacial physical properties
• Research Institution: Kagoshima University
• Principal Investigator: Nozawa Kazuki 鹿児島大学, 理工学域理学系, 准教授 (00448763)
• Co-Investigator(Kenkyū-buntansha): 藤井 伸平 鹿児島大学, 理工学域理学系, 教授 (90189994)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: 準結晶 / 結晶成長 / 第一原理計算

Outline of Final Research Achievements

We investigated the atomic structure and electronic states of single-element quasi-periodic ultra-thin films formed on the Ag-In-Yb quasicrystal using a non-empirical calculation based on quantum mechanics. Both Pb and Bi form single-element quasi-periodic layers occupying part of atomic sites of the substrate, but scanning tunneling microscopy (STM) had observed that the structures and adsorption sequences of these films were different. We revealed in this study that the reason why Pb and Bi exhibit different structures in the initial stage of the adsorption. We pointed out that some adsorbed atoms which are not detected by STM play a role in the formation of the quasi-periodic films. We reported that a single-element quasi-periodic film of Ag can be formed on the same substrate. We verified the accuracy of a method to determine the stable adsorption structure on aperiodic surfaces within the ordinary band calculation method.

Free Research Field

物性理論、計算物質科学

Academic Significance and Societal Importance of the Research Achievements

本研究の成果により、PbおよびBi単元素準結晶薄膜の成長過程においてSTMで観測されない吸着原子層が関与することが明らかになるなど、単元素準結晶の実現に向けて基礎的知見を積み上げることができた。これまで確認されていない元素（Ag）でも単元素準結晶薄膜が得られる可能性を示したことで、この分野の研究に新たな可能性をもたらした。また、本研究で用いた計算手法について詳細な検証を行ったことで、非周期結晶表面や欠陥のある表面に適用できる新たな手法を確立できた。