2018 Fiscal Year Research-status Report
Hydrodynamic behaviour of electrons on the surface of superfluid helium
Project/Area Number |
18K13506
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Research Institution | Okinawa Institute of Science and Technology Graduate University |
Principal Investigator |
BADRUTDINOV Alex 沖縄科学技術大学院大学, メカニカルエンジニアリング&マイクロファブリケーション・サポートセクション, ナノファブリケーション サポート エキスパート (30727540)
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Project Period (FY) |
2018-04-01 – 2020-03-31
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Keywords | electrons on helium / 2D electron system / electron viscosity |
Outline of Annual Research Achievements |
I performed further experimental study of the effect of non-Ohmic current splitting in three-terminal microchannel devices. Specifically, I studied in detail dependence of the effect on temperature and surface electron density. I found that the effect disappears above 0.7 K, independent of density. At lower temperatures, the effect has a density dependence, and gets weaker as density is increasing. I also proved reproducibility of the effect by observing all essential features on two different samples of similar design. And I performed some theoretical analysis of the obtained data. At the moment I have two working hypotheses to explain the effect. One is my original hypothesis, relating the effect to hydrodynamic properties of electron system, such as electron viscosity. Another hypothesis, which emerged based on the new data, is that the effect may be a manifestation of strong coupling between surface electrons and surface capillary waves of helium, and non-Ohmic transport of electrons is driven by interaction with helium surface. I continue working on data analysis and theoretical modelling, to clarify the origin of the effect.
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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 state of the project is in line with the original plan. Originally planned experimental activities are finished, data analysis is in progress.
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Strategy for Future Research Activity |
The research plan for coming year consists of two parts. The first part is to continue data analysis, formulate a model explaining the observed phenomena, and prepare for publication and submit a manuscript. I believe that already available experimental data should be enough to come to unambiguous conclusion about the origin of the effect. The second part is to try to extend experimental capabilities to be able to accumulate higher surface electron densities in microchannel devices. If successful, this will contribute valuable data to the current project. At the same time, it is of much interest for other applications with electrons on helium. The difficulty to achieve higher densities is largely technological. I need to fabricate devices with smoother surfaces, shallower channels and smaller inter-electrode gaps. To achieve that, I am planning to employ new material for electrodes (amorphous metal TaWSi, known to have very smooth surface) and e-beam lithography for patterning. Once the samples are successfully fabricated, they will be tested at low temperature by standard measurement techniques.
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Causes of Carryover |
In the FY 2018 I could get some pieces of equipment from other sources. Though I used more than expected for consumables, the total spent amount was less than expected.
In the FY 2019, I am planning to spend most of the budget for consumables for fabrication, according to the plan to further develop device fabrication technique. Also, I am planning to invite a collaborator to our institute for about a week, to help with modelling. One conference trip is also planned.
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Research Products
(3 results)