2013 Fiscal Year Research-status Report
Unconventional Superconductivity in semiconductor systems
| Project/Area Number |
25800197
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| Research Category |
Grant-in-Aid for Young Scientists (B)
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| Research Institution | 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 – 2015-03-31
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| Keywords | Topological Insulators / Topological SC / Semiconductors / Unconventional SC |
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| Research Abstract |
The aim of this project is to find new possibly unconventional superconductivity (SC) in so-called semiconducting and insulating materials induced by doping. As a starting point topological insulator materials were chosen. In this new class of materials firstly (Pb0.77Sn0.23)Se was targeted and doped with various elements. Tl doping was found to induce SC but after a comprehensive study of this particular doping series it was found that not the bulk phase but a minority phase was responsible for the SC and hence this system was given up.
The study of the superconducting topological insulator CuxBi2Se3, already started before this project, was continued by a specific-heat study of the x dependence of the superconducting phase. It seems that the system behaves different for small and large Cu concentrations x but the complex intercalation chemistry of this system makes an explanation of the possibly topological superconducting phase difficult. The second currently discussed possible topological superconducting system is more promissing: Sn1-xInxTe. SnTe exhibits a ferroelectric instability along with a structural phase transition. It was found that the superconducting phase of this system shows a peculiar In-doping dependence and that the superconducting pairing mechanism is possibly different in the ferroelectric phase below x ~0038 from that in the cubic phase. Moreover there are indications that close to the critical In concentration of x ~ 0.038 the SC may be unconventional whereas away from it in either direction the system seems to be “more” conventional.
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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
So far the research project is running as planned.
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| Strategy for Future Research Activity |
In the next fiscal year I'd like to focus on newly found topological systems as, e.g., the recently emergent compound Cd3As2 which is discussed in terms of Dirac physics ("Weyl semimetal") and exhibits a very high electron mobility. Here also doping is indicated to possibly induce superconductivity. First the growth recipe has to be set which should be no problem for the parent material and some of the substitution series, e.g, Zn-doping, since the material has already been known for a long time. Before starting the growth several safety measures have to be taken into account. This has already started (preparing a suitable glove box, safe pelletizing and cutting, a.s.o.). Possibly additional items to handle Arsenic have to be bought.
The further research plan depends strongly on the results of the material synthesis and if there is a superconducting phase or not. Further potentially interesting materials include doped BiTeI and doped dichalcogenides.
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| Expenditure Plans for the Next FY Research Funding |
The main reason for the remaining money is that the instruments purchased for this project were cheaper than initially estimated as well as that the business trips to conferences were also cheaper than expected.
The remaining money will be used together with the money requested in FY 2014 for an additional instrument needed for the planned research.
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Research Products
(4 results)
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[Journal Article] Anomalous dressing of Dirac fermions in the topological surface state of Bi2Se3, Bi2Te3, and Cu-doped Bi2Se32013
Author(s)
T. Kondo, Y. Nakashima, Y. Ota, Y. Ishida, W. Malaeb, K. Okazaki, S. Shin, M. Kriener, S. Sasaki, K. Segawa, and Y. Ando
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Journal Title
Phys. Rev Lett.
Volume: 110
Pages: 217601-1~5
DOI
Peer Reviewed
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