2014 Fiscal Year Research-status Report
Unconventional Superconductivity in semiconductor systems
| Project/Area Number |
25800197
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| Research Institution | The Institute of Physical and Chemical Research |
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Principal Investigator |
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)
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| Project Period (FY) |
2013-04-01 – 2016-03-31
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| Keywords | Topological Insulators / Topological SC / Semiconductors / Unconventional SC |
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| Outline of Annual Research Achievements |
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)
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
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.
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| Strategy for Future Research Activity |
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.
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| Causes of Carryover |
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.
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| Expenditure Plan for Carryover Budget |
The remaining budget will be used for consumables and to present the obtained results at domestic conferences.
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