| 研究課題/領域番号 |
22K18270
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| 研究機関 | 沖縄科学技術大学院大学 |
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研究代表者 |
Dani Keshav 沖縄科学技術大学院大学, フェムト秒分光法ユニット, 准教授 (80630946)
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| 研究期間 (年度) |
2022-06-30 – 2025-03-31
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| キーワード | Extreme UV light source / High order / harmonic generation / XUV-PEEM / Nano-APRES / Twisted 2D materials / Moire pattern |
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| 研究実績の概要 |
Nanoscale spatial resolution imaging and nano-ARPES with the XUV photon source with high enough photon flux has been the goal of this Kakenhi proposal. Such a resolution allows the complete investigation of the nanoscale variations in the electronic structure of a material. In this fiscal year, we have finished setting up a new XUV beamline, which provides a flux density of 4 x1018 photons/sec/cm2 that is two-order in magnitude higher than what we have previously done. We have coupled this beamline to an electron microscope. In our initial test runs, we demonstrated that we are capable of doing imaging with XUV photon reaching a spatial resolution better than 100nm and we can also perform APRES with few micron spatial resolution. We have also started a study on twisted 2D materials, preliminary result shows that we can image and resolve different ferroelectric domains in the moire structure.
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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
2: おおむね順調に進展している
理由
Objectives of this research include (A) development of a XUV light source with photon flux density orders of magnitude higher than what is currently available; (B) to utilize this new light source to do time resolved PEEM and nano-ARPES measurement, and (C) to explore moire structure and their excitons in 2D heterostructure.
In this fiscal year, we have progressed rather smoothly, given that we are doing quite well in every aspect. Below is a summary of what we have achieved so far.
(A) We have finished building a new XUV beamline in Jan 2023. We have achieved a spot size of 32 x 7 um on the sample and reaching a flux density up to 4 x1018 photons/sec/cm2, which is two orders better than our previous light source (1x 1016 photons/sec/cm2) and we are just one order short from what we are aiming for.
(B) We have coupled the beamline to our electron microscope, we have succeeded in doing XUV-PEEM reaching spatial resolution better than 100nm, and we could already perform micro-APRES on samples within our setup with few micron meter resolution.
(C) We have started the study of twisted 2D materials. As preliminary results, we have successfully visualized the ferroelectric domains in a moire superlattice.
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| 今後の研究の推進方策 |
In this year, we will continue our work towards the three objectives, (A) to further optimize the flux density of our XUV light source, we should potentially gain another order of magnitude in flux density by (1) increasing the repetition rate of the light source, (2) by improving the phase matching condition and laser parameters like changing gas jet diameter, pump wavelength, pulse duration and gas pressure, and (3) to further reduce the spot size, by alignment using a wave front sensor.
(B) With a brighter light source, we could perform XUV-PEEM and do TR-XUV-PEEM measurement at higher efficiency. With higher flux, we would also investigate the possibility of performing high resolution nano-ARPES.
(C) Our preliminary result from the 2D moire material is very promising. This year we will continue our work to investigate the domain and domain wall structure in these moire materials, we also planned to image the localized excitons that forms in the moire super lattice using TR-XUV-PEEM and TR-ARPES techniques.
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| 次年度使用額が生じた理由 |
The travel on this grant to Stanford FY22 was postponed by just a few months to Apr-May 2023, for two reasons (i) to make some progress on research, and (ii) to coordinate with invited talks at MRS Spring Meeting (Apr. 2023, San Francisco) and CLEO (May 2023, San Jose), where some of the progress on this grant research was presented.
To make progress on research, we didn't present this work at JSAP in FY2022, but will do so in FY23.
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