2022 Fiscal Year Annual Research Report
Optical response of van der Waals heterointerface by symmetry engineering
| Project/Area Number |
22J22007
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| Allocation Type | Single-year Grants |
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| Research Institution | The University of Tokyo |
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Principal Investigator |
董 禹 東京大学, 工学系研究科, 特別研究員(DC1)
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| Project Period (FY) |
2022-04-22 – 2025-03-31
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| Keywords | 3R MoS2 / bulk photovoltaic effect / strain |
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| Outline of Annual Research Achievements |
In the past year, I focused on bulk piezophotovoltaic effect in 3R-MoS2. By straining 3R-MoS2, the rotational symmetry is broken, and we expect an in-plane polarization to arise. Thus, we observed the bulk piezophotovoltaic effect. The bulk photovoltaic (BPV) response is greatly enhanced by strain and the BPV coefficient increases at least two orders by 0.2% of strain. This work was published in Nature Nanotechnology in Nov 2022. Last year, I also carried out a research internship in Xiaodong Xu lab, University of Washington, where I learnt many useful skills in device fabrication and optical set-up construction.
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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 progress of my research is smoothly proceeded as planned, though the specific material we researched on is adjusted. By the symmetry engineering strategy, we strained 3R MoS2, which has no inversion symmetry, to create an in-plane polarization. We successfully observed enhanced bulk photovoltaic effect (bulk piezophotovoltaic effect) and second harmonic generation to confirm the in-plane polarization. Besides 3R-MoS2, I have other two projects regarding on ferroelectric NbOI2 and magnet/magnet interface CrSBr/CrPS4 to carry on. In general, the progress of my research progress is good and on schedule.
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| Strategy for Future Research Activity |
In this year, I will continue on the research on ferroelectric NbOI2 and magnet/magnet interface CrSBr/CrPS4. The goal for NbOI2 is to observe switchable circular photogalvanic effect, and I am trying to clarify the influence of strain on NbOI2. As to CrSBr/CrPS4 interface, both of them are 2D magnets, but one has in-plane magnetic order and the other has out-of-plane magnetic order. The aim is to observe in-plane polarization induced by non-collinear spin structure via inverse DM effect. It is another important demonstration for the symmetry engineering strategy in van der Waals heterostructure.
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