Microscopic fluctuations in electron-nuclei coupled systems observed by Spin Noise Spectroscopy-Nuclear Magnetic Resonance Technique

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K03812
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 13020:Semiconductors, optical properties of condensed matter and atomic physics-related
• Research Institution: Hokkaido University
• Principal Investigator: Kaji Reina 北海道大学, 工学研究院, 助教 (40640751)
• Co-Investigator(Kenkyū-buntansha): 足立 智 北海道大学, 工学研究院, 教授 (10221722)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 半導体 / 核スピン分極 / 核四極子相互作用 / 量子ドット

Outline of Final Research Achievements

To develop a new spectroscopic technique “SNS-NMR” that combines the features of Spin Noise Spectroscopy (SNS), which specializes in studying for the electron spin in thermal equilibrium, and Nuclear Magnetic Resonance (NMR), which has a proven track record in the study of nuclear spin, we worked on the construction and improvement of optical systems, selection of test samples, and fabrication of strain-tuning devices. Contrary to initial expectations, the formation of giant nuclear spin polarization, which greatly exceeds the external magnetic field, was detected in n-AlGaAs bulk. In the magneto-photoluminescence measurement of single quantum dots, which was carried out as a subproject, we evaluated the correlation time of the hyperfine interaction which couples the electron and nuclear spins in the localization volume and obtained new knowledge about the nuclear quadrupole interaction.

Free Research Field

半導体スピン物性

Academic Significance and Societal Importance of the Research Achievements

混晶化や格子歪みに起因する核四極子効果は，サブテスラの磁場領域において，核スピン系のエネルギー構造を大きく変化させる重要な相互作用の一つである．これとの関連が濃厚なn-AlGaAsバルクにおける巨大核偏極形成は報告例がなく，非常に興味深い発見と言える．また，単一量子ドット発光の時間分解測定から，核四極子相互作用の主軸成分が電子-核スピンダイナミクスで果たす役割が明らかになった．これらを含む一連の成果は，将来的に半導体中の電子-核スピン結合系の応用領域を拡大する上で大いに役立つものであり，高い学術的・社会的意義がある．