Investigations on formation mechanisms of spontaneous excitons in excitonic insulators

2022 Fiscal Year Final Research Report

• Project/Area Number: 21K20358
• Research Category: Grant-in-Aid for Research Activity Start-up
• Allocation Type: Multi-year Fund
• Review Section: 0202:Condensed matter physics, plasma science, nuclear engineering, earth resources engineering, energy engineering, and related fields
• Research Institution: Institute for Molecular Science
• Principal Investigator: Fukutani Keisuke 分子科学研究所, 光分子科学研究領域, 助教 (10706021)
• Project Period (FY): 2021-08-30 – 2023-03-31
• Keywords: 励起子絶縁体 / 光電子分光 / 自発的励起子

Outline of Final Research Achievements

Excitons are the unstable particles within semiconductor materials that are formed transiently under light irradiations. In recent years, a new phase of matter called "excitonic insulator" has garnered much attentions. In the excitonic insulator phase, the electrons and holes are spontaneously bound to form an excitons and exist as a permanent particle.
In this research project, by directly observing the behaviors of these spontaneously formed excitons near their formation boundary, I have revealed that the formation of these spontaneously formed excitons gradually occur under the appropriate material properties and conditions, while their physical sizes and the binding energies are progressively changed.

Free Research Field

物性物理学

Academic Significance and Societal Importance of the Research Achievements

本課題の研究により、自発的励起子がその消失に近づくにつれて、段階的に密度が減少するだけでなく励起子自体のサイズが増大しておりその束縛力の減少が連続的に起こっているであろうとの示唆を得た。これは、自発的励起子がこれまで考えられてきた特殊な物質のみならず、より広く産業応用されている半導体物質等においても物質設計により発生させることが可能であることを示唆する重要な成果であると考える。