半導体二次元電子系と超伝導体の接合における新奇輸送現象の探索と解明

• Project Area: Frontiers of materials science spun from topology
• Project/Area Number: 18H04218
• Research Category: Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area)
• Allocation Type: Single-year Grants
• Research Institution: The University of Tokyo
• Principal Investigator: 中村 壮智 東京大学, 物性研究所, 助教 (50636503)
• Project Period (FY): 2018-04-01 – 2020-03-31
• Project Status: Completed (Fiscal Year 2019)
• Budget Amount: ¥6,500,000 (Direct Cost: ¥5,000,000、Indirect Cost: ¥1,500,000); Fiscal Year 2019: ¥3,250,000 (Direct Cost: ¥2,500,000、Indirect Cost: ¥750,000); Fiscal Year 2018: ¥3,250,000 (Direct Cost: ¥2,500,000、Indirect Cost: ¥750,000)
• Keywords: 超伝導接合 / 二次元電子系 / 半導体 / スピン軌道相互作用 / スピンホール効果 / ジョセフソン効果 / Zitterbewegung / 運動量位相 / 超伝導 / メゾスコピック系 / スピン物性

Outline of Annual Research Achievements

本研究ではInAsの二次元電子系を用いた超伝導接合に面内磁場や電流などの外場を加えることで超伝導体/強磁性体/超伝導体接合で見られるような0-π転移やスピン三重項超伝導現象を観測を目指している。本年はInAs量子井戸の側面に超伝導電極を接合した試料について、ジョセフソン効果の超伝導臨界電流の、磁場、電流、電場依存性を調べた。昨年度と同様に超伝導電流と直交するスピン流によっても臨界電流は減少することが複数の試料で確かめられた。スピン偏極電流を注入した時の数値計算の結果からZitterbewegungと呼ばれるスピン回転を伴う電子の蛇行運動が二次元電子系に生じており、試料の形状からこれが抑制の原因であることを指摘した。
また、トレンチ型のゲートを持つ試料を作成し、二次元電子面平行に電場を加え臨界電流の変化を調べた。その結果、ゲートに負の電圧を加えた場合には試料の電子濃度が低下し、それに伴う二次元電子系の抵抗の上昇と臨界電流の減少を観測したが、驚くべきことに、正の電圧を加えた場合にも臨界電流が減少することを観測した。正電圧下では試料抵抗は減少しており、電子濃度やチャネル数では臨界電流の変化は説明できない。この新奇な効果の起源は現時点では明らかになっていないが、電子の波数に分布が生じることで経路による運動量位相が干渉を引き起こしていると考えて現在数値計算を進めている。
また原子層半導体である二硫化モリブデンにレーザー照射を行い構造相転移を引き起こすことでトポロジカル絶縁体化されることを示した。このトポロジカル絶縁体は酸化しやすいものの比較的安定であり試料の作成や加工が容易であることから、現在は超伝導電極を接合した素子の作成を行っており、マヨラナフェルミオンの検出に向けて研究を進めている。

Research Progress Status

令和元年度が最終年度であるため、記入しない。

Strategy for Future Research Activity

令和元年度が最終年度であるため、記入しない。

Research Products

• [Journal Article] Room-temperature quantum spin Hall phase in laser-patterned few-layer 1T'-MoS2 (2020)
  • Author(s): N. Katsuragawa, M. Nishizawa, T. Nakamura, T. Inoue, S. Pakdel, S. Maruyama, S. Katsumoto, J. J. Palacios, J. Haruyama
  • Journal Title: Communications Materials Volume: -
  • Peer Reviewed / Open Access
• [Journal Article] Topological Insulating States in Graphene with Low-Amount Nanoparticle Decoration (2019)
  • Author(s): 春山 純志、勝本 信吾、中村 壮智
  • Journal Title: Butsuri Volume: 74 Issue: 12 Pages: 839-844
  • DOI: 10.11316/butsuri.74.12_839
  • NAID: 130007843282
  • ISSN: 0029-0181, 2423-8872
  • Year and Date: 2019-12-05
  • Peer Reviewed
• [Journal Article] Laser-Beam-Patterned Topological Insulating States on Thin Semiconducting MoS2 (2019)
  • Author(s): H. Mine, A. Kobayashi, T. Nakamura, T. Inoue, S. Pakdel, D. Marian, E. Gonzalez-Marin, S. Maruyama, S. Katsumoto, A. Fortunelli, J. J. Palacios, and J. Haruyama
  • Journal Title: Physical Review Letters Volume: 123 Issue: 14 Pages: 146803-146803
  • DOI: 10.1103/physrevlett.123.146803
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Evidence for Spin-Triplet Electron Pairing in the Proximity-Induced Superconducting State of an Fe-Doped InAs Semiconductor (2019)
  • Author(s): Nakamura Taketomo, Anh Le Duc, Hashimoto Yoshiaki, Ohya Shinobu, Tanaka Masaaki, and Katsumoto Shingo
  • Journal Title: Physical Review Letters Volume: 122 Issue: 10 Pages: 107001-107001
  • DOI: 10.1103/physrevlett.122.107001
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Spin Filtering Magnetoresistance in Double‐Well Resonant Structures (2019)
  • Author(s): Nakamura Taketomo, Hashimoto Yoshiaki, Ke Tong, and Katsumoto Shingo
  • Journal Title: physica status solidi (b) Volume: なし Issue: 6 Pages: 1800560-1800560
  • DOI: 10.1002/pssb.201800560
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Evidence for a quantum spin Hall phase in graphene decorated with Bi2Te3 nanoparticles (2018)
  • Author(s): Hatsuda K.、Mine H.、Nakamura T.、Li J.、Wu R.、Katsumoto S.、Haruyama J.
  • Journal Title: Science Advances Volume: 4 Issue: 11
  • DOI: 10.1126/sciadv.aau6915
  • Peer Reviewed / Open Access
• [Journal Article] 半導体の電気伝導におけるZitterbewegung（ジグザグ運動） (2018)
  • Author(s): 中村壮智, 勝本信吾
  • Journal Title: 日本物理学会誌 Volume: 73 Pages: 776-781
  • NAID: 130007652830
  • Peer Reviewed
• [Presentation] Spin Blockade and Magnetoresistance in Double QuantumWell Diode with Inverted Electric Field (2019)
  • Author(s): Yoshiaki Hashimoto, Tong Ke, Taketomo Nakamura, and Shingo Katsumoto
  • Organizer: Compound Semiconductor Week 2019
  • Int'l Joint Research
• [Presentation] Control of electron spin at spin-resolved quantum Hall edges (2019)
  • Author(s): Takase Shimizu, Yoshiaki Hashimoto, Taketomo Nakamura, Akira Endo, and Shingo Katsumoto
  • Organizer: Compound Semiconductor Week 2019
  • Int'l Joint Research
• [Presentation] The Josephson effect in InAs quantum wells with the spin Hall effect (2019)
  • Author(s): Taketomo Nakamura, Yoshiaki Hashimoto, and Shingo Katsumoto
  • Organizer: Compound Semiconductor Week 2019
  • Int'l Joint Research
• [Presentation] Superconductor connection to InAs two-dimensional electrons with accumulation edges (2019)
  • Author(s): Makoto Onizaki, Yoshiaki Hashimoto, Taketomo Nakamura, and Shingo Katsumoto
  • Organizer: Compound Semiconductor Week 2019
  • Int'l Joint Research
• [Presentation] Anomalous suppression of the Josephson effect in InAs 2D electron systems due to the spin Hall effect (2019)
  • Author(s): Taketomo Nakamura, Yoshiaki Hashimoto, and Shingo Katsumoto
  • Organizer: Spintech X
  • Int'l Joint Research
• [Presentation] Spin manipulation in quantum Hall edge states through spin-orbit interaction (2019)
  • Author(s): T.Shimizu, Y.Hashimoto, T.Nakamura, A. Endo, and S. Katsumoto
  • Organizer: Spintech X
  • Int'l Joint Research
• [Presentation] トレンチ型サイドゲート付き超伝導/InAs二次元電子ガス/超伝導接合の輸送特性 (2019)
  • Author(s): 鬼嵜誠, 橋本義昭, 中村壮智, 勝本信吾
  • Organizer: 日本物理学会 2019年秋季大会
• [Presentation] Ti/MoS2界面における超伝導状態の磁気履歴効果 (2019)
  • Author(s): 相川夕美花, 石黒亮輔, 遠藤彰, 中村壮智, 橋本義昭, 清水貴勢, 津村公平, 柏谷聡, 高柳英明, 勝本信吾
  • Organizer: 日本物理学会 2019年秋季大会
• [Presentation] The Josephson effect on the multiterminal junctions of InAs 2D electron system (2019)
  • Author(s): T. Nakamura
  • Organizer: 3rd EPiQS-TMS alliance workshop on Topological Phenomena in Quantum Materials
  • Int'l Joint Research / Invited
• [Presentation] Side gate control of supercurrent in an InAs quantum well (2019)
  • Author(s): M. Onizaki, Y. Hashimoto, T. Nakamura, S. Katsumoto
  • Organizer: 3rd EPiQS-TMS alliance workshop on Topological Phenomena in Quantum Materials
  • Int'l Joint Research
• [Presentation] Landau-Zener mixing of spin-resolved quantum Hall edge channels (2019)
  • Author(s): T.Shimizu, Y.Hashimoto, T.Nakamura, A. Endo, and S. Katsumoto
  • Organizer: 3rd EPiQS-TMS alliance workshop on Topological Phenomena in Quantum Materials
  • Int'l Joint Research
• [Presentation] Supercurrent Reduction through Voltage-control of Kinetic Phase (2019)
  • Author(s): M. Onizaki, Y. Hashimoto, T. Nakamura, S. Katsumoto
  • Organizer: International School and Symposium on Nanoscale Transport and phoTonics 2019
  • Int'l Joint Research
• [Presentation] The Josephson Effect with Transverse Spin Current in an InAs Quantum Well (2019)
  • Author(s): T. Nakamura
  • Organizer: 14th Asia Pacific Physics Conference
  • Int'l Joint Research / Invited
• [Presentation] Anomalous reduction of the supercurrent due to the electric field gradient (2019)
  • Author(s): Taketomo Nakamura, M. Onizaki, Y. Hashimoto, and S. Katsumoto
  • Organizer: International Conference on Topological Materials Science 2019
  • Int'l Joint Research
• [Presentation] Gate control of intra-Landau level transition and observation of spin precession at quantum Hall state (2019)
  • Author(s): Takase SHIMIZU, Yoshiaki HASHIMOTO, Taketomo NAKAMURA, Akira ENDO, and Shingo KATSUMOTO
  • Organizer: MATERIALS RESEARCH MEETING 2019
  • Int'l Joint Research
• [Presentation] Spin-Blockade and Rashba-Resonance in a Double Quantum Well Diode (2019)
  • Author(s): Taketomo NAKAMURA, Yoshiaki HASHIMOTO, and Shingo KATSUMOTO
  • Organizer: MATERIALS RESEARCH MEETING 2019
  • Int'l Joint Research
• [Presentation] In-plane field and current dependence of the Josephson effect in Nb/InAs/Nb junctions (2019)
  • Author(s): T. Nakamura, Y. Hashimoto, and S. Katsumoto
  • Organizer: Topological Phases and Functionality of Correlated Electron Systems 2019
  • Int'l Joint Research
• [Presentation] Supercurrent on accumulation edges of an InAs quantum well (2019)
  • Author(s): M. Onizaki, T. Nakamura, Y. Hashimoto, and S. Katsumoto
  • Organizer: Topological Phases and Functionality of Correlated Electron Systems 2019
  • Int'l Joint Research
• [Presentation] Control of electron spin through quantum Hall edge-spin entanglement (2019)
  • Author(s): T. Shimizu, Y. Hashimoto, T. Nakamura, A. Endo, and S. Katsumoto
  • Organizer: Topological Phases and Functionality of Correlated Electron Systems 2019
  • Int'l Joint Research
• [Presentation] 電流注入によるジョセフソン効果の制御 (2019)
  • Author(s): 中村壮智
  • Organizer: 日本物理学会第74回年次大会
  • Invited
• [Presentation] 量子ホールエッジ状態間の電子スピン非断熱遷移と位相の独立制御 (2019)
  • Author(s): 清水貴勢, 橋本義昭, 中村壮智, 遠藤彰, 勝本信吾
  • Organizer: 日本物理学会第74回年次大会
• [Presentation] n-i-p-i-n 三重障壁構造におけるスピンブロッケード (2019)
  • Author(s): 橋本義昭, 中村壮智, 勝本信吾
  • Organizer: 日本物理学会第74回年次大会
• [Presentation] Ti/ MoS2界面における輸送特性 (2019)
  • Author(s): 相川夕美花, 遠藤彰, 中村壮智, 清水貴勢, 成田智絵, 津村公平, 柏谷聡, 高柳英明, 勝本信吾, 石黒亮輔
  • Organizer: 日本物理学会第74回年次大会
• [Presentation] 量子ポイントコンタクト付き超伝導/InAs二次元電子ガス/超伝導接合の伝導特性 (2019)
  • Author(s): 鬼嵜誠, 橋本義昭, 中村壮智, 勝本信吾
  • Organizer: 日本物理学会第74回年次大会
• [Presentation] The Josephson effect in Nb/InAs/Nb junctions under in-plane magnetic fields (2018)
  • Author(s): T. Nakamura, Y. Hashimoto, and S. Katsumoto
  • Organizer: 34th International Conference on the Physics of Semiconductors
  • Int'l Joint Research
• [Presentation] In-plane resonant spin-filtering with Rashba-Dresselhaus interaction (2018)
  • Author(s): S. Katsumoto, Y. Hashimoto, X. Yao, Y. Iwasaki, and T. Nakamura
  • Organizer: 34th International Conference on the Physics of Semiconductors
  • Int'l Joint Research
• [Presentation] Doubled conductance in quantum Hall edge transport probably on electron-hole channels generated by Andreev reflection (2018)
  • Author(s): M. Onizaki, T. Nakamura, A. Endo, Y. Hashimoto, and S. Katsumoto
  • Organizer: 34th International Conference on the Physics of Semiconductors
  • Int'l Joint Research
• [Presentation] Filling factor dependence of non-adiabatic spin transition among quantum Hall edge states (2018)
  • Author(s): T. Shimizu, Y. Hashimoto, T. Nakamura, A. Endo, and S. Katsumoto
  • Organizer: 34th International Conference on the Physics of Semiconductors
  • Int'l Joint Research
• [Presentation] The in-plane field effects for the Josephson effect in two-dimensional electron system (2018)
  • Author(s): T. Nakamura
  • Organizer: Oxide Superspin International School 2018
  • Int'l Joint Research / Invited
• [Presentation] InAs二次元電子系におけるジョセフソン効果の面内磁場依存性 (2018)
  • Author(s): 中村壮智, 橋本義昭, 勝本信吾
  • Organizer: 日本物理学会2018年秋季大会
• [Presentation] Rashba-Dresselhaus複合相互作用によるトンネル異方性磁気抵抗II (2018)
  • Author(s): 橋本義昭, 松林幸宏, 中村壮智, 勝本信吾
  • Organizer: 日本物理学会2018年秋季大会
• [Presentation] 強磁性半導体中のスピン三重項超伝導 (2018)
  • Author(s): 中村壮智
  • Organizer: メゾスコピック系における非平衡スピン輸送の微視的理解とその制御
  • Invited