Special Seminar

Resistively-Detected NMR & Quantum Transport In Semiconductor Quantum Systems

Fri, 02 Jun 2017 2:30 PM
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Special Seminar
Resistively-Detected NMR & Quantum Transport In Semiconductor Quantum Systems

Yoshiro Hirayama
Department of Physics, Graduate School of Science, Tohoku University

June 2, 2017 at 2:30pm in P8445.2

Synopsis

Recent progress of resistively-detected nuclear-magnetic-resonance (RDNMR) provides us a versatile tool to study physics in semiconductor quantum systems. The RDNMR needs dynamic nuclear polarization (DNP) and sensitive detection of nuclear polarization. In semiconductor two-dimensional systems, the DNP is achieved by a current flow through a domain structure appearing in the quantum Hall ferromagnet (QHF) at the spin phase transition of ν = 2/3 (GaAs) or ν = 2 (InSb). The DNP can also be achieved by a quantum Hall breakdown. The situation necessary for the DNP provides us sensitive detection of the nuclear polarization. Especially, a modulation of the domain structure by the DNP changes resistance value dramatically in the QHF. The important role of the chiral edge channel on RDNMR is recently addressed by using the InSb ν = 2 QHF. The DNP can also be induced by irradiation of a circularly polarized light. It is suggestive to compare resistive and optical detections of the DNP process. In bilayer system, one can confirm canted spin state by using RDNMR. The linear dispersion of electron spin results in a strong interaction between ensemble of nuclear spins and ensemble of electron spins. The RDNMR study has been extended to microscopic systems. In a triple-gate QPC, where one-dimensional confinement can be manipulated precisely, rich characteristics including change of RDNMR line-shape are demonstrated. Local manipulation of nuclear spins by nanoprobe scanning gate and its application to nuclear resonance imaging are also addressed.

 

 

 

Biography:
Having received his Bachelor, Master, and Ph.D degrees in Engineering from the University of Tokyo in 1978, 1980, and 1983, respectively, Prof. Yoshiro Hirayama joined NTT Basic Research Laboratories in 1983. In NTT, he served as Group Leader, Distinguished Technical Member and Executive Manager. From July 2006, he moved to Tohoku University. His current interests are transport properties of semiconductor heterostructures and nanostructures, especially putting emphasis on carrier interactions and coherent control including manipulation of nuclear spins in semiconductors. He was a leader of a several NEDO and JST projects concerning semiconductor quantum transport, carrier interaction, and quantum coherent systems. He was the project leader of the ERATO-JST “Nuclear Spin Electronics” (2007- 2015) project, where electron and nuclear spin interactions were extensively studied. Currently acting as a project leader of KKENHI, Grant-in-Aid for Scientific Research on Innovative Area “Science of Hybrid Quantum System” (2015-2019), he is also a coordinator of Graduate Program in Spintronics and sub-coordinator of Interdepartmental Doctoral Degree Program for Multi-dimensional Materials Science Leaders of Tohoku University. His publication record includes more than 340 refereed journal articles and book chapters related to semiconductor heterostructures and nanostructures.