Creation of the next-generation semiconductor-based nano-spin electronics devices

2011 Fiscal Year Final Research Report

• Project/Area Number: 20686002
• Research Category: Grant-in-Aid for Young Scientists (A)
• Allocation Type: Single-year Grants
• Research Field: Applied materials science/Crystal engineering
• Research Institution: The University of Tokyo
• Principal Investigator: OHYA Shinobu 東京大学, 大学院・工学系研究科, 准教授 (20401143)
• Project Period (FY): 2008 – 2011
• Keywords: スピントロニクス / 量子ヘテロ構造

Research Abstract

This project has opened up new possibilities for ferromagnetic-semiconductor GaMnAs-based quantum devices, and has clarified the valence-band structure of GaMnAs and its related materials. We have achieved a high tunneling magnetoresistance(TMR) up to 175% at 2. 6K in the GaMnAs/AlMnAs/GaMnAs magnetic tunnel junctions. This value is the highest value ever reported in the same temperature region in the GaMnAs-based magnetic tunnel junctions. We fabricated three-terminal GaMnAs quantum-well(QW) devices, and succeeded in controlling the quantum levels and the magneto current ratio by modulating the voltage of the QW electrode. By using the resonant tunneling spectroscopy, we have systematically clarified the valence band structure of GaMnAs for the first time.

Research Products

• [Journal Article] Nearlynon-magnetic valence band of theferromagnetic semiconductor GaMnAs (2011)
  • Author(s): S. Ohya, K. Takata, and M. Tanaka
  • Journal Title: Nature Phys Volume: 7 Pages: 342-347
  • Peer Reviewed
• [Journal Article] Valence-Band Structure of the Ferromagnetic-Semiconductor GaMnAs Studied by Spin-Dependent Resonant Tunneling Spectroscopy (2010)
  • Author(s): S. Ohya, I. Muneta, P. N. Hai, and M. Tanaka
  • Journal Title: Phys. Rev. Lett. Volume: 104
  • Peer Reviewed
• [Journal Article] Quantum-level control in a III-V-based ferromagnetic-semiconductor heterostructure with a GaMnAs quantum well and double barriers (2009)
  • Author(s): S. Ohya, I. Muneta, and M. Tanaka
  • Journal Title: Appl. Phys. Lett. Volume: 96
  • Peer Reviewed
• [Journal Article] GaMnAs-based magnetic tunnel junctions with an AlMnAs barrier (2009)
  • Author(s): S. Ohya, I. Muneta, P. N. Hai, and M. Tanaka
  • Journal Title: Appl. Phys. Lett. Volume: 95
  • Peer Reviewed
• [Presentation] Valence-bandstructure of the ferromagnetic semiconductor GaMnAs (2011)
  • Author(s): S. Ohya, K. Takata, I. Muneta, P. N. Hai, Y. Xin, and M. Tanaka
  • Organizer: 5th International Workshop on Spin Currents
  • Place of Presentation: Sendai International Center, Sendai, Japan
  • Year and Date: 2011-07-25
• [Presentation] Resonant tunneling spectroscopy and valence-bandpicture of the ferromagnetic semiconductor GaMnAs (2011)
  • Author(s): S. Ohya, I. Muneta, K. Takata, Y. Xin, P. N. Hai, and M. Tanaka
  • Organizer: BC-03, IEEE International Magnetics Conference(Intermag 2011)
  • Place of Presentation: Taipei International Convention Center, Taipei, Taiwan
  • Year and Date: 2011-04-26
• [Presentation] Valence-band structure of the ferromagnetic semiconductor GaMnAs investigated by resonant tunneling spectroscopy (2011)
  • Author(s): S. Ohya
  • Organizer: Applied Physics Society(APS) March Meeting 2011
  • Place of Presentation: Dallas, USA
  • Year and Date: 2011-03-23
• [Presentation] Spindependent resonant tunneling in III-V-based ferromagnetic-semiconductor heterostructures (2010)
  • Author(s): M. Tanaka and S. Ohya
  • Organizer: 55th Annual Conferenceon Magnetism and Magnetic Materials
  • Place of Presentation: Atlanta, USA
  • Year and Date: 20101114-18
• [Presentation] Spin-dependent Resonant Tunneling in III-V-based Ferromagnetic-Semiconductor Quantum Heterostructures (2008)
  • Author(s): S. Ohya
  • Organizer: 2008 International Conference on Solid State Devices and Materials(SSDM 2008)
  • Place of Presentation: Tsukuba International Congress Center, Japan
  • Year and Date: 2008-09-26
• [Book] Spintronic Devices Based on Semiconductors (2011)
  • Author(s): M. Tanaka and S. Ohya, Bhattacharya P, Fornari R, and Kamimura H
  • Total Pages: 540-562
  • Publisher: Elsevier
• [Book] IIIV and Group-IV-Based Ferromagnetic Semiconductors for Spintronics (2010)
  • Author(s): M. Tanaka, S. Ohya, Y. Shuto, S. Yada, and S. Sugahara, Andrews DL, Scholes, GD and Wiederrecht GP
  • Total Pages: 447-462
  • Publisher: Elsevier
• [Book] Properties and functionalities of MnAs/III-V hybrid and composite structures (2008)
  • Author(s): M. Tanaka, M. Yokoyama, P-N. Hai, and S. Ohya
  • Total Pages: 500
  • Publisher: Academic Press
• [Remarks] 研究室ホームページ
  • URL: http://www.cryst.t.u-tokyo.ac.jp/ohya/index.html
• [Remarks] プレスリリースS. Ohya, et al., Nature Phys. 7, 342-347(2011)に掲載された論文記事について、様々なメディアで報道された:「東大、様々な強磁性半導体GaMnA試料においてフェルミ準位の位置とバンド構造を系統的に解明」、日経プレスリリース、マイコミジャーナル、YAHOO! Japanニュース、chem-index、Gooマネー、東大プレスリリースなど