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Numerical study of critical phenomena in disordered topological quantum systems

Research Project

Project/Area Number 19K14607
Research Category

Grant-in-Aid for Early-Career Scientists

Allocation TypeMulti-year Fund
Review Section Basic Section 13010:Mathematical physics and fundamental theory of condensed matter physics-related
Research InstitutionTohoku University

Principal Investigator

Kobayashi Koji  東北大学, 金属材料研究所, 特任助教 (10711905)

Project Period (FY) 2019-04-01 – 2023-03-31
Project Status Discontinued (Fiscal Year 2022)
Budget Amount *help
¥3,380,000 (Direct Cost: ¥2,600,000、Indirect Cost: ¥780,000)
Fiscal Year 2022: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000)
Fiscal Year 2021: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000)
Fiscal Year 2020: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000)
Fiscal Year 2019: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Keywordsトポロジカル量子系 / ワイル半金属 / 量子相転移 / 異常ホール効果 / 量子輸送現象 / 臨界現象 / 輸送現象 / 相転移 / トポロジカル物質
Outline of Research at the Start

近年注目されているトポロジカル量子系における、乱れ誘起の量子相転移の性質を調べる。トポロジカル量子系の臨界特性は理論的な取り扱いが困難であるため、本研究ではトポロジカル量子系の特殊な臨界現象を見るための計算手法の改良、及び新しい手法の提案を行い、また各種相転移点の臨界特性を精密な数値計算により明らかにする。これにより、乱れのあるトポロジカル量子系の性質を系統的に理解するための理論構築を行う。

Outline of Final Research Achievements

We have numerically studied critical properties and transport phenomena in disordered topological quantum systems.
We proposed a new analytical method for critical phenomena in topological semimetals and improved numerical methods for investigating transport phenomena in the presence of disorder. Using those methods, we investigated in detail the critical and transport properties of Dirac/Weyl semimetals, which had been unclear because of the technical challenges. In addition, we carried out fundamental research and proposals for spintronics device applications of topological quantum systems.

Academic Significance and Societal Importance of the Research Achievements

トポロジカル量子系は乱れに対する頑強性が特徴とされているが、その具体的な性質の研究には技術的困難が伴う。本研究では新しい計算手法を提案すると同時に実際にそれを用いて新奇な輸送特性の性質などを調べたことで、乱れたトポロジカル量子系を効率的に研究する道筋を示した。
特にワイル半金属における新奇な磁気抵抗やホール効果の研究は、スピントロニクスデバイスへの応用を考える上で重要な基礎理論となるのみならず、デバイス応用へ向けた課題と利点を明らかにするなど、実験研究の進展も刺激するものである。

Report

(4 results)
  • 2022 Final Research Report ( PDF )
  • 2021 Annual Research Report
  • 2020 Research-status Report
  • 2019 Research-status Report
  • Research Products

    (20 results)

All 2022 2021 2020 2019 Other

All Int'l Joint Research (1 results) Journal Article (6 results) (of which Int'l Joint Research: 1 results,  Peer Reviewed: 6 results,  Open Access: 3 results) Presentation (13 results) (of which Int'l Joint Research: 5 results)

  • [Int'l Joint Research] ミュンヘン大学(ドイツ)

    • Related Report
      2021 Annual Research Report
  • [Journal Article] Intrinsic and Extrinsic Anomalous Hall Effects in Disordered Magnetic Weyl Semimetal2022

    • Author(s)
      Kobayashi Koji、Nomura Kentaro
    • Journal Title

      Journal of the Physical Society of Japan

      Volume: 91 Issue: 1

    • DOI

      10.7566/jpsj.91.013703

    • NAID

      210000159516

    • Related Report
      2021 Annual Research Report
    • Peer Reviewed / Open Access
  • [Journal Article] Wannier-based implementation of the coherent potential approximation with applications to Fe-based transition metal alloys2022

    • Author(s)
      Ito Naohiro、Nomoto Takuya、Kobayashi Koji、Mankovsky Sergiy、Nomura Kentaro、Arita Ryotaro、Ebert Hubert、Koretsune Takashi
    • Journal Title

      Physical Review B

      Volume: 105 Issue: 12 Pages: 125136-125136

    • DOI

      10.1103/physrevb.105.125136

    • Related Report
      2021 Annual Research Report
    • Peer Reviewed / Int'l Joint Research
  • [Journal Article] Ferromagnetic-electrodes-induced Hall effect in topological Dirac semimetals2021

    • Author(s)
      Kobayashi Koji、Nomura Kentaro
    • Journal Title

      Physical Review Research

      Volume: 3 Issue: 3 Pages: 0330231-11

    • DOI

      10.1103/physrevresearch.3.033023

    • Related Report
      2021 Annual Research Report
    • Peer Reviewed / Open Access
  • [Journal Article] Quantum Hall effect induced by chiral Landau levels in topological semimetal films2021

    • Author(s)
      Nguyen D.-H.-Minh、Kobayashi Koji、Wichmann Jan-Erik R.、Nomura Kentaro
    • Journal Title

      Physical Review B

      Volume: 104 Issue: 4 Pages: 0453021-12

    • DOI

      10.1103/physrevb.104.045302

    • Related Report
      2021 Annual Research Report
    • Peer Reviewed
  • [Journal Article] Ballistic transport in disordered Dirac and Weyl semimetals2020

    • Author(s)
      Kobayashi Koji、Wada Miku、Ohtsuki Tomi
    • Journal Title

      Physical Review Research

      Volume: 2 Issue: 2

    • DOI

      10.1103/physrevresearch.2.022061

    • Related Report
      2020 Research-status Report
    • Peer Reviewed / Open Access
  • [Journal Article] Robust magnetotransport in disordered ferromagnetic kagome layers with quantum anomalous Hall effect2019

    • Author(s)
      Kobayashi Koji、Takagaki Masaki、Nomura Kentaro
    • Journal Title

      Physical Review B

      Volume: 100 Issue: 16

    • DOI

      10.1103/physrevb.100.161301

    • Related Report
      2019 Research-status Report
    • Peer Reviewed
  • [Presentation] Wannier関数を用いたCPA計算の実装2022

    • Author(s)
      伊東直洋, 野本拓也, 小林浩二, Sergiy Mankovsky, 野村健太郎, 有田亮太郎, F, Hubert Ebert, 是常隆
    • Organizer
      日本物理学会第77回年次大会
    • Related Report
      2021 Annual Research Report
  • [Presentation] ワイル半金属における内因性ホール効果と縦伝導度(Intrinsic Hall conductance and longitudinal conductance in Weyl semimetals)2021

    • Author(s)
      小林浩二,野村健太郎
    • Organizer
      第140回金属材料研究所講演会
    • Related Report
      2021 Annual Research Report
  • [Presentation] トポロジカルディラック半金属を用いた連続的抵抗制御:トポロジカルディラックメモリスタ(Continuous control of resistance with topological Dirac semimetals: topological Dirac memristor)2021

    • Author(s)
      小林浩二,野村健太郎
    • Organizer
      日本物理学会2021年秋季大会
    • Related Report
      2021 Annual Research Report
  • [Presentation] Relation Between Hall and Longitudinal Conductances in Disordered Magnetic Weyl Semimetal Thin Films2021

    • Author(s)
      K. Kobayashi, K. Nomura
    • Organizer
      EP2DS-24/MSS-20
    • Related Report
      2021 Annual Research Report
    • Int'l Joint Research
  • [Presentation] ワイル半金属における内因性・外因性ホール効果と縦伝導度2021

    • Author(s)
      小林浩二、野村健太郎
    • Organizer
      日本物理学会第76回年次大会
    • Related Report
      2020 Research-status Report
  • [Presentation] Ballistic feature in disordered Dirac and Weyl semimetals2021

    • Author(s)
      K. Kobayashi, M. Wada, T. Ohtsuki
    • Organizer
      APS March Meeting 2021
    • Related Report
      2020 Research-status Report
    • Int'l Joint Research
  • [Presentation] Critical behavior of ballistic transport in disordered Dirac and Weyl semimetals2020

    • Author(s)
      Koji Kobayashi, Miku Wada, Tomi Ohtsuki
    • Organizer
      Localisation 2020
    • Related Report
      2020 Research-status Report
    • Int'l Joint Research
  • [Presentation] 強磁性電極を接続したトポロジカルディラック半金属のホール磁気抵抗効果2020

    • Author(s)
      小林浩二、野村健太郎
    • Organizer
      日本物理学会2020年秋季大会
    • Related Report
      2020 Research-status Report
  • [Presentation] トポロジカルディラック半金属における強磁性電極誘起ホール磁気抵抗効果2020

    • Author(s)
      小林浩二、野村健太郎
    • Organizer
      第139回金属材料研究所講演会
    • Related Report
      2020 Research-status Report
  • [Presentation] 強磁性電極によるトポロジカルディラック半金属中の量子異常ホール効果2020

    • Author(s)
      小林浩二、野村健太郎
    • Organizer
      日本物理学会第75回年次大会
    • Related Report
      2019 Research-status Report
  • [Presentation] ワイル半金属中のランダムな磁区による磁気抵抗効果2019

    • Author(s)
      小林浩二、野村健太郎
    • Organizer
      日本物理学会2019年秋季大会
    • Related Report
      2019 Research-status Report
  • [Presentation] Robust magnetotransport in disordered quantum anomalous Hall Kagome layers2019

    • Author(s)
      K. Kobayashi, M. Takagaki, K. Nomura
    • Organizer
      Summit of Materials Science 2019: SMS2019
    • Related Report
      2019 Research-status Report
    • Int'l Joint Research
  • [Presentation] Robust magnetoresistance in disordered quantum anomalous Hall Kagome layers2019

    • Author(s)
      K. Kobayashi, M. Takagaki, K. Nomura
    • Organizer
      International Conference on Topological Materials Science 2019 (TopoMat 2019)
    • Related Report
      2019 Research-status Report
    • Int'l Joint Research

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Published: 2019-04-18   Modified: 2024-01-30  

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