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2014 年度 実施状況報告書

Unconventional Superconductivity in semiconductor systems

研究課題

研究課題/領域番号 25800197
研究機関独立行政法人理化学研究所

研究代表者

KRIENER Markus  独立行政法人理化学研究所, 創発物性科学研究センター, 研究員 (60447919)

研究期間 (年度) 2013-04-01 – 2016-03-31
キーワードTopological Insulators / Topological SC / Semiconductors / Unconventional SC
研究実績の概要

The following systems were examined:
The CuxBi2Se3 project was started before this project. During the last two years further indications that it is an unconventional superconductor (SC) were found. (3 paper published, 1 submitted in FYs 2013, 2014)
In the In-doped SnTe SC the nature of the SC seems to change with the Indium concentration possibly due to an interplay with the ferroelectric phase in SnTe which is suppressed by doping. Just above the critical In concentration where the ferroelectric phase disappears, the SC might be unconventional. (1 published paper)
Tl-doping into the (Pb0.77Sn0.23)Se system yielded superconductivity but only in a minority phase and hence it was not a bulk effect. (project was abandoned)
The semiconductor WSe2 becomes metallic upon Ta-doping but again there was no indication of SC. However, the thermal conductivity in codoped (WTa)(SeTe)2 was found to be strongly suppressed at room temperature. The system exhibits figure of merits of about 0.35 at elevated temperatures for x ~ 0.03. (1 paper published)
GeTe also exhibits a ferroelectric instability which is suppressed by doping. Moreover GeTe itself superconducts at very low temperatures. We tried Mn-doping into this system which leads to a ferromagnetic phase. There were no indications that the SC in GeTe survives the doping but a different interesting new feature was found: Depending on the exact growth recipe two different ferromagnetic phases can be obtained for small Mn concentrations. This is possibly due to a spinodal decomposition. (2 papers in preparation)

現在までの達成度 (区分)
現在までの達成度 (区分)

2: おおむね順調に進展している

理由

The project was running as planned although in the last year of this project no new superconductors were found. Instead different interesting effects by doping into semiconductors were detected and traced.

今後の研究の推進方策

The GeTe project is still ongoing / publications are currently under preparation. The remaining (forwarded) money into this FY will be used for consumables and to present the obtained results at domestic conferences.

次年度使用額が生じた理由

I did not attend any conference abroad in FY 2014. Therefore the part of the funding reserved for international conference attendances remained unspent in FY 2014.

次年度使用額の使用計画

The remaining budget will be used for consumables and to present the obtained results at domestic conferences.

  • 研究成果

    (3件)

すべて 2015 2014

すべて 雑誌論文 (2件) (うち査読あり 2件、 謝辞記載あり 2件) 学会発表 (1件)

  • [雑誌論文] Modification of electronic structure and thermoelectric properties of hole-doped tungsten dichalcogenides2015

    • 著者名/発表者名
      M. Kriener, A. Kikkawa, T. Suzuki, R. Akashi, R. Arita, Y. Tokura, and Y. Taguchi
    • 雑誌名

      Phys. Rev. B

      巻: 91 ページ: 075205-1~10

    • DOI

      10.1103/PhysRevB.91.075205

    • 査読あり / 謝辞記載あり
  • [雑誌論文] Doping-dependent charge dynamics in CuxBi2Se32014

    • 著者名/発表者名
      L.J. Sandilands, A.A. Reijnders, M. Kriener, K. Segawa, S. Sasaki, Y. Ando, and K.S. Burch
    • 雑誌名

      Phys. Rev. B

      巻: 90 ページ: 094503-1~6

    • DOI

      10.1103/PhysRevB.90.094503

    • 査読あり / 謝辞記載あり
  • [学会発表] Doping Effect on the Thermoelectric Properties of WSe1.6Te0.42014

    • 著者名/発表者名
      M. Kriener
    • 学会等名
      69th Autumn Meeting of the Physical Society of Japan
    • 発表場所
      Kasugai, Japan
    • 年月日
      2014-09-07

URL: 

公開日: 2016-06-01  

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