Ferromagnetism and magnetoelectric cross-correlation in magnetic semiconductor (Ge,Mn)Te with broken inversion symmetry

• Project/Area Number: 17H02770
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Applied materials
• Research Institution: Institute of Physical and Chemical Research
• Principal Investigator: Taguchi Yasujiro 国立研究開発法人理化学研究所, 創発物性科学研究センター, グループディレクター (70301132)
• Project Period (FY): 2017-04-01 – 2021-03-31
• Project Status: Completed (Fiscal Year 2020)
• Budget Amount: ¥17,810,000 (Direct Cost: ¥13,700,000、Indirect Cost: ¥4,110,000); Fiscal Year 2020: ¥2,600,000 (Direct Cost: ¥2,000,000、Indirect Cost: ¥600,000); Fiscal Year 2019: ¥3,380,000 (Direct Cost: ¥2,600,000、Indirect Cost: ¥780,000); Fiscal Year 2018: ¥3,380,000 (Direct Cost: ¥2,600,000、Indirect Cost: ¥780,000); Fiscal Year 2017: ¥8,450,000 (Direct Cost: ¥6,500,000、Indirect Cost: ¥1,950,000)
• Keywords: 強磁性 / 超伝導 / トポロジカル転移 / 反転対称性 / 半導体 / 極性構造 / 磁性半導体 / 希薄磁性半導体

Outline of Final Research Achievements

We have investigated ferromagnetism and superconductivity induced by doping various ions into GeTe with broken inversion symmetry. We succeeded in obtaining a ferromagnetic transition temperature higher than 200 K by doping Mn. In addition, high transition temperatures can be obtained by doping as many Mn ions as possible while keeping rhombohedral structure.
We also succeeded in inducing metal-semiconductor-superconductor transition by doping In into GeTe. It turned out that carrier type changes at a critical In concentration where the structure changes from rhombohedral to cubic, the superconductivity emerges in the region of electron-type carrier, and the valence state of In changes from 3+ to 1+.

Academic Significance and Societal Importance of the Research Achievements

磁性半導体の強磁性転移温度を増大するための戦略あるいは物質合成指針を提唱することに成功した。これによって、より高い転移温度の磁性半導体が開発され、スピントロニクスに応用されることによって、より低消費電力での革新的なエレクトロニクスの実現に資する可能性がある。
また、単純な2元系の超伝導体において価数スキップが生じて、超伝導転移温度の増大と関係している可能性を示した。これによって、高い超伝導転移温度を有する物質の設計・開発に資する可能性がある。

Research Products

• [Journal Article] Evolution of Electronic States and Emergence of Superconductivity in the Polar Semiconductor GeTe by Doping Valence-Skipping Indium (2019)
  • Author(s): M. Kriener, M. Sakano, M. Kamitani, M. S. Bahramy, R. Yukawa, K. Horiba, H. Kumigashira, K. Ishizaka, Y. Tokura, and Y. Taguchi
  • Journal Title: Phys. Rev. Lett. Volume: 124 Issue: 4
  • DOI: 10.1103/physrevlett.124.047002
  • Peer Reviewed
• [Journal Article] Enhanced ferromagnetic transition temperature induced by a microscopic structural rearrangement in the diluted magnetic semiconductor Ge_1-xMn_xTe (2017)
  • Author(s): M. Kriener, T. Nakajima, Y. Kaneko, A. Kikkawa, D. Hashizume, K. Kato, M. Takata, T. Arima, Y. Tokura, and Y. Taguchi
  • Journal Title: Physical Review B Volume: 95 Issue: 22 Pages: 1-12
  • DOI: 10.1103/physrevb.95.224418
  • Peer Reviewed / Int'l Joint Research
• [Presentation] About the enhancement of superconductivity in InTe (2021)
  • Author(s): M. Kriener, M.S. Bahramy, Yl Tokura, and Y. Taguchi
  • Organizer: 日本物理学会 第76回年次大会
• [Presentation] Superconductivity in InTe revisited (2019)
  • Author(s): Markus Kriener、上谷学、田口康二郎、十倉好紀
  • Organizer: 日本物理学会第74回年次大会
• [Presentation] Band-filling-controlled superconductor-insulator-superconductor transition in doped GeTe (2018)
  • Author(s): Markus Kriener、坂野昌人、石坂香子、田口康二郎、十倉好紀
  • Organizer: 日本物理学会秋季大会
• [Presentation] Enhanced superconductivity in the polar semiconductor GeTe induced by doping (2018)
  • Author(s): M. Kriener
  • Organizer: 72nd Autumn Meeting of the Physical Society of Japan