2018 Fiscal Year Research-status Report
Heavy group III, IV, and V elements triangular lattice atomic layers on semiconductor surfaces - a new kind of 2D Dirac materials
| Project/Area Number |
18K04941
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| Research Institution | Kyushu University |
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Principal Investigator |
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| Project Period (FY) |
2018-04-01 – 2021-03-31
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| Keywords | spin-orbit coupling / Rashba effect / graphene / SiC |
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| Outline of Annual Research Achievements |
In accordance with research plan for 2018, we have investigated dense triangular lattice atomic overlayers (TLALs) of group III, IV, and V heavy elements on SiC(0001) by experimental and computational methods. The following has results have been achieved:
1. The stability and electronic structure of Ge, Bi, In, Pb, Sn, Sb, and Tl TLALs has been studied by first principles calculations. It has been found that Ge, Pb, Sn, Sb, and In TLALs are stable, while Bi and Tl are not. The electronic structures of all the elements are qualitatively similar exhibiting peculiarly spin-polarized states. For practical applications, such as spintronic devices, the difference in variously spin-polarized of group III (spin-polarized Dirac cone) and IV elements (Rashba-type parabolic spin splitted states) around Fermi level is important.
2. Currently the attempts to generate pure TLAL structures experimentally have not been successful.
3. Intercalated graphene/TLAL/SiC(0001) system has been realized for Sn and studied by ARPES and STM technique at collaborators research facilities. ARPES and spin-ARPES electronic structure results are in perfect agreement with calculated data. One of the milestone results is that graphene/(1x1)-Sn/SiC(0001) is the first observed system with spin-polarized system bands remaining stable upon exposure to air.
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| Current Status of Research Progress |
Current Status of Research Progress
3: Progress in research has been slightly delayed.
Reason
While computational part of research project is successfully proceeding according to plan, the progress in experimental part of the project is moving slightly behind schedule due to the difficulties concerning experimental equipment setup procedures, management and support. As we are planning on improving our experimental research environment in the next year, we'll catch up the progress.
As the results obtained so far represent new and important features in the field of spin-polarized two dimensional materials, a lot of efforts in the past financial year were also concentrated on preparation and publication of the results in scientific journals.
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| Strategy for Future Research Activity |
In the following period we are planning significantly improve our experimental research environment, by introducing more experimental apparatus in our laboratory facility which will enable more sophisticated analysis as well as more direct machine time devoted to this particular project. In particular we are planning to attempt a setup of a refurbished STM chamber which will allow direct structure analysis on site.
As calculation results reveal that not all heavy group III, IV, and V elements are making stable triangular overlayers, in experiments we will concentrate on those which are most interesting (In, Sn, Pb).
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