応用物理学輪講 I
12月16日
[注意事項]
発表の10日前までに　office[at]ap.t.u-tokyo.ac.jp　宛てに「氏名」「指導教員」「発表題目（英語）」「要旨（英語）」「発表言語（英語または日本語）」を送付して下さい。
発表日
2022年12月16日（金）16：50～18：50

Aグループ

座長
濱尾　智
指導
教員名
石坂　香子　教授
座長
吹上　義樹
指導
教員名
長谷川　幸雄　教授
発表者名 吉永　享太
指導教員名 木村　隆志　准教授
発表題目（英語） Design of Wolter Mirror for Spectro-microscopic Imaging with Single-shot Soft X-rays
要旨（英語） X-ray microscopy is suitable for visualizing the internal structure of samples due to its high penetrating power and spatial resolution. Moreover, X-ray spectro-microscopy can analyze chemical states and magnetic structures, thus used in a wide range of fields, mainly in materials science. With higher temporal resolution, it has potential to become an essential technology for in-situ/operand observation of unknown phenomena such as reactions in living organisms and fuel cells.
In this study, we develop a spectro-microscopic system with a single-shot pulse of soft X-rays using a Wolter mirror[1][2] and multi-aperture grating. This optical system allows simultaneous imaging of multicolor soft X-rays, with photon energies corresponding to absorption edges of each element included in samples.
We aim to construct this system at SPring-8 BL07LSU, the soft X-ray beamline with multiple undulators. For this purpose, we have designed a Wolter mirror and multi-aperture grating by optical simulation and conducted the proof-of-principle experiment using visible light.

[1]H. Wolter, Ann.Phys. 445(1-2), 94-114 (1952).
[2]T. Kimura et al., Opt. Express 30, 26220-26228 (2022).
発表言語 日本語
発表者名 韓　東学
指導教員名 石坂　香子　教授
発表題目（英語） The Role of Magnetic Edge Dislocation in the Ultrafast Conical-Ferromagnetic Phase Transition in Co9Zn9Mn2
要旨（英語） Study of optically induced ultrafast magnetic dynamics is becoming a significant topic in modern magnetism. Particularly, fs-µs dynamics of skyrmions and conical magnetic structures formed by Dzyaloshinskii-Moriya interaction attracts much attention from the viewpoint of nanoscale magnetic manipulation. However, characteristic length scales (e.g. size, period) of such magnetic structures are typically of ~100 nm scale, which is difficult to resolve by conventional optical ultrafast probes. Ultrafast electron microscopy, which combines optical pump-probe method and transmission electron microscopy (TEM), enables observation of photoinduced dynamics with sufficient spatiotemporal resolution. In particular, Lorentz TEM can visualize conical magnetic structure as striped pattern, by utilizing the electron beams deflected by the local magnetic fields in materials.
In this study, we investigate the magnetic dynamics of photoinduced conical-ferromagnetic phase transition in a room-temperature chiral magnet Co9Zn9Mn2, by using the nanosecond pulsed electrons as probe. 190 fs pulsed light of 531 nm wavelength strongly suppressed the conical magnetic structure within the temporal resolution 10 ns. We also found that an isolated magnetic edge dislocation strongly affects the relaxation dynamics that continues more than 1 µs. In the presentation, I will discuss possible explanations of the effect of magnetic edge dislocation based on experimental results and previous studies.
発表言語 日本語
発表者名 佐藤　秀樹
指導教員名 志村　努　教授
発表題目（英語）
要旨（英語）
発表言語

Bグループ

座長
馬場　智大
指導
教員名
鹿野田　一司　教授
座長
竹内　晴哉
指導
教員名
酒井　啓司　教授
発表者名 米虫　遼太郎
指導教員名 川﨑　雅司　教授
発表題目（英語） Fabrication and optical property of cupurous halide film
要旨（英語） Cupurous halidesemiconductors are focused because of its large optical response. In particular, CuCl has strong excitonic properties, while CuI is a transparent conductor.On the other hand, in general, synthesize halide film is difficult because halides are highly reactive and have high vapor pressure, and methods for fabricating high-quality thin films are still in the developmental stage. Recently, however, a method for fabricating CuI thin films at a level where Laue fringes can be observed has been established using Molecular Beam Epitaxy.In this presentation, I will show you the experimental results of fabricating high quality CuI thin film and discuss the exciton properties of CuI and CuCl as I compare them.
発表言語 日本語
発表者名 姜　東彦
指導教員名 小林　洋平　教授
発表題目（英語） Few cycle pulses generation with a mode-locked Yb doped fiber laser by nonlinear pulse compression
要旨（英語） Fiber lasers show various advantages over solid states lasers, including high average power, high frequency, low cost, and compactness. Ultrashort pulses with high peak power have enabled applications in both fundamental science and industrial applications including microscopy, materials processing, and high-harmonic generation. However, generating few-cycle pulses is still challenging for fiber lasers because of their limited gain bandwidths. We designed a scheme to achieve ultrashort pulses by putting pulses which have broad bandwidths into the fiber.
Here, we explain the concept of 10-fs ultrashort pulses generation. In this method, a 100Mhz mode-locked Yb fiber laser is amplified with a homemade Yb-Doped Fiber Amplifier (YDFA). And pulses are spectrally broadened with a bare fiber and compressed with chirped mirrors which compensate for the second-order dispersion. By putting the compressed pulse into the second fiber and compressing again, the ultrashort pulses are obtained.
We also explain the experimental results of generation of 0.6W average power and ultrashort pulses with a duration of 10fs.
発表言語 日本語
発表者名 張　凌志
指導教員名 求　幸年　教授
発表題目（英語） Theoretical study of heterostructure of Kitaev materials
要旨（英語） The Kitaev spin model with bond-dependent anisotropic interactions on a honeycomb lattice has attracted much attention for the exact spin liquid ground state with fractional Majorana excitations. To realize it in materials, several candidates have been studied for the so-called spin-orbital coupled Mott insulators. Recently, to explore exotic properties arising from the coupling between spin and charge in the Kitaev materials, heterostructure of atomically thin films of a candidate α-RuCl3 with graphen was studied both experimentally and theoretically. While such heterostructure is not limited to graphen but able to include other van der Waals materials, the possibility has not been fully examined thus far. In our study, we aim to investigate heterostructure of α-RuCl3 and other van der Waals materials including magnets. In this presentation, I will introduce previous studies on heterostructure of the Kitaev candidate materials. In addition, I will discuss my preliminary results on monolayer and bilayer of α-RuCl3 obtained by first-principles calculations with structural optimization.
発表言語 英語
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