High speed spin transport control with vector-field pulse shaping

2020 Fiscal Year Final Research Report

• Project/Area Number: 18K03487
• 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: Tokyo University of Agriculture and Technology
• Principal Investigator: Ito Hironori 東京農工大学, 工学(系)研究科(研究院), 特任助教 (60724127)
• Co-Investigator(Kenkyū-buntansha): 三沢 和彦 東京農工大学, 工学(系)研究科(研究院), 教授 (80251396)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: フェムト秒レーザー / 光位相制御 / 偏光制御 / 半導体 / トポロジカル絶縁体 / スピントロニクス

Outline of Final Research Achievements

The polarization, frequency, and phase, which are physical quantities of light, were manipulated using the original pulse shaping of this research group. We tried optical-carrier control that is directly connect to the conduction electron spin, electron velocity, and local electron concentration. First, we constructed a measurement system that enables light irradiation and transport measurement of semiconductor quantum wells at low temperatures. The pulse shaping generated a polarization-twisted pulse whose polarization rotates at a terahertz frequency, and irradiated the semiconductor quantum well. As a result, the angular momentum of light was transferred to the spin of conduction electrons, and we succeeded in observing the spin current from the photovoltage signal. Furthermore, we developed a terahertz pump probe system through international joint research to observe the spin current of topological insulator.

Free Research Field

光物性

Academic Significance and Societal Importance of the Research Achievements

レーザー光の持つ波形をフェムト秒単位で正確に制御する技術を駆使し、半導体中の電子の持つスピンを操作する新たな方法を発見した。さらに電子の持つスピンに応じてその運動を光で操作することに成功した。この方法は電子の位置や運動方向およびスピンまで電子の持つ全ての物理的自由度を制御できるため、光の新たな活用法として広く応用が期待される。