2018 Fiscal Year Final Research Report
Research on formation of quantum ordered states in ultra cold electron-hole system by spectroscopy of electron states under extreme environments
| Project/Area Number |
26247049
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (A)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Condensed matter physics I
|
|---|
| Research Institution | The University of Tokyo |
|---|
Principal Investigator |
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
吉岡 孝高 東京大学, 大学院工学系研究科(工学部), 准教授 (70451804)
|
|---|
| Research Collaborator |
MORITA Yusuke
KONISHI Kuniaki
ARASHIDA Yusuke
|
|---|
| Project Period (FY) |
2014-04-01 – 2018-03-31
|
| Keywords | 光物性 / 励起子 / 光電子分光 |
|---|
| Outline of Final Research Achievements |
We realized mid-infrared absorption imaging of paraexcitons in cuprous oxide crystal at a temperature of 64 mK via the application of a dilution refrigerator. We observed a Bose-Einstein condensate of paraexcitons below 400 mK by visualizing the exciton cloud in real space using absorption imaging. We also extracted the lifetime, mobility, and diffusion constant of trapped paraexcitons below 1 K from measurements of space- and time-resolved luminescence spectra of paraexcitons.
Furthermore, we constructed a system for laser-based angle-resolved photoelectron spectroscopy (ARPES) using a time-of-flight (ToF) electron analyzer. We also achieved the highest energy resolution of ARPES using the ToF analyzer. The high yield of our analyzer enabled us to observe photo-excited states of topological insulators and semiconductors.
We also succeeded in evaluating the carrier density of Fermi-degenerate electron-hole droplets by measuring mid-infrared dielectric response and ultraviolet emission.
|
| Free Research Field |
光物性
|
| Academic Significance and Societal Importance of the Research Achievements |
極低温領域における精密分光、時間分解分光、吸収分光の開拓に挑戦し、半導体中の高密度電子正孔系が作り出す基底状態、協働現象、動的特性について新たな知見を得た。これにより、バルク半導体での励起子ボース凝縮を直接可視化することに成功し、60年以上の懸案に明確な結論を与えた。また従来の測定法に比べ極めて高収率な光電子分光装置を立ち上げ、高エネルギー分解能測定を実現した。光励起された電子のエネルギーと運動量のダイナミクスを高感度直接観測でき、固体が光励起により示す様々な機能について、電子系の振る舞いを通じて理解する新規手法を得たことは、物理学に限らず光化学など幅広い分野にとって有意義な成果である。
|
