Investigation of the electron and nuclear spin dynamics in quantum Hall regime by spatial and time resolved magneto-optical Kerr measurement

2015 Fiscal Year Final Research Report

• Project/Area Number: 25287069
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Partial Multi-year Fund
• Section: 一般
• Research Field: Condensed matter physics I
• Research Institution: Chiba University
• Principal Investigator: Oto Kenichi 千葉大学, 理学(系)研究科(研究院), 教授 (30263198)
• Co-Investigator(Kenkyū-buntansha): NAKAJIMA Makoto 大阪大学, レーザーエネルギー学研究センタ, 准教授 (40361662)
• Co-Investigator(Renkei-kenkyūsha): MINO Hirofumi 千葉大学, 普遍教育センター, 准教授 (40323430)
• Project Period (FY): 2013-04-01 – 2016-03-31
• Keywords: 量子ホール効果 / スピン / Kerr回転 / 核スピン偏極 / イメージング

Outline of Final Research Achievements

We developed the magneto-optical Kerr rotation imaging system operating below 0.5 K by using dilution refrigerator to investigate the electron spin polarization in quantum Hall (QH) regime. The dynamic nuclear polarization (DNP) by the QH breakdown current and the dynamics of DNP relaxation were studied by means of the spatial and time resolved Kerr rotation measurements. The spatial pattern of the QH breakdown current can be imaged as a DNP distribution profile. We also investigated the electron spin polarization in GaAs/AlGaAs HEMT structures, where the extent of Kerr rotation angle is negligibly smaller than that in the quantum well structures, by using Sagnac interferometer. We confirmed the electron spin polarization at the filling factor 3 can be evaluated by the Kerr rotation measurement with the electron density modulation. We also studied the electron transport near the edge channels in QH regime under the optical vortex irradiation.

Free Research Field

物性実験