応用物理学輪講 I
10月27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
2023年10月27日（金）16：50～18：50

Aグループ

座長
大橋　悠生
指導
教員名
福谷　克之　教授
座長
大村　昂輝
指導
教員名
川﨑　雅司　教授
発表者名 葛西　章也
指導教員名 求　幸年　教授
発表題目（英語） An introduction to three-dimensional topological spin textures.
要旨（英語） The two-dimensional structure of magnetic skyrmions, which are vortex-shaped structures of localized spins, is expected to be applied as a carrier of information in a race-track memory due to its topological stability and controllability by electric current. However, skyrmions also have the disadvantage of being affected by the skyrmion Hall effect. On the other hand, magnetic Hopfions, which are three-dimensional topological structures, are considered more suitable for device applications than skyrmions because their three-dimensional nature prevents the "Hopfion Hall effect" from occurring. In this way, three-dimensional topological spin structures have new functionalities that are not possible in two or one dimensions.
発表言語 日本語
発表者名 片岡　大輔
指導教員名 川﨑　雅司　教授
発表題目（英語） Fabrication of Dy2Ru2O7 thin film
要旨（英語） Pyrochlore oxides have been receiving continuous attentions in recent years due to the fascinating magnetic structures and frustrated interactions. Notably, the spin-ice compound Dy2Ti2O7 has been the subject of extensive investigation, characterized by the presence of a solitary magnetic moment-bearing ion. It might be of interest to turn our focus to my research subject, Dy2Ru2O7, where both Dy and Ru ions are magnetic. However, in general, it is difficult to fabricate ruthenate thin films due to the high volatility of ruthenium. As the result, there have been no thin film fabrication reports on Ln2Ru2O7. In this presentation, I will show you the experimental results of fabricating Dy2Ru2O7 thin film and explain my future research plans.
発表言語 日本語
発表者名 川本　知輝
指導教員名 香取　秀俊　教授
発表題目（英語） Miniaturization of an atom source with a magneto-optical trap in a square pyramidal configuration
要旨（英語） Optical lattice clocks can measure the transition frequency of reference atoms with an accuracy up to the $10^{-18} level, making them suitable for gravitational potential measurements on a centimeter scale. There is a growing initiative to make these clocks portable and facilitate remote comparisons of gravitational potentials. A key step toward this goal involves miniaturizing the magneto-optical trap (MOT), which is the initial step in the atomic cooling process of optical lattice clocks. To generate cold atoms in MOT, it is important to maintain the equilibrium of the radiation pressure inside the MOT.

We discovered that a configuration in which five laser beams are directed from each surface of a four-sided pyramid towards a specific point, meets the required conditions. This configuration can be realized by just one laser and one specially designed mirror, resulting in the miniaturization of an atom source. Based on this idea, we determined the optimal arrangement of both the laser and the magnetic field and set up the overall experimental system. In this presentation, we explain our concept of the a four-sided pyramidal MOT and show the latest results of our experiment.
発表言語 日本語

Bグループ

座長
大野　亮汰
指導
教員名
長谷川　達生　教授
発表者名 大村　洸翔
指導教員名 志村　努　教授
発表題目（英語） Relationship between structure size and phase modulation in metasurface
要旨（英語） Metasurface is a artificial structure to control the wavefront of light by creating sub-wavelength structures (meta-atoms) on the surface.
This technology is expected to make conventional optical elements thinner and lighter. However, its design relies on a method of iterating simulation and optimization that requires relatively large computational resources.
Therefore, we are searching for a model that can estimate the amount of phase modulation with a relatively simple calculation, using the size of the meta-atom and its distance from other meta-atoms as parameters. Here we present an overview of our research, comparing the results of simulations with waveguide models using the equivalent refractive index method.
発表言語 日本語
発表者名 岡崎　淳哉
指導教員名 長谷川　幸雄　教授
発表題目（英語） Exploration for ferromagnetic Pd by spin-polarized scanning tunneling microscopy
要旨（英語） Bulk Pd is non-magnetic material but close to ferromagnetic according to the Stoner criterion. Nikalasson et al. theoretically calculated magnetic moment of Pd thin films on Ag(001) substrate and concluded that Pd thin films may have magnetic moment on certain film thickness because quantum well states in Pd thin films enhanced the density of states at the Fermi energy. Sakuragi et al. experimentally demonstrated the ferromagnetism of Pd(100) thin films and investigated their thickness dependence. However, the surface spin distribution of Pd thin films has not been directly observed. The purpose of this study is to investigate the structure, electronic states, and magnetic properties of Pd films using scanning tunneling microscopy/spectroscopy (STM/S) and spin-polarized STM (SP-STM).
発表言語 日本語
発表者名 小口　尚志
指導教員名 井手上　敏也　准教授
発表題目（英語） Epitaxial growth and magnetic properties of CrxTaSe2
要旨（英語） Transition-metal dichalcogenide (TMD) is a group of layered materials labelled with MX2 (M: transition metal, X: chalcogen), which is a promising platform for 2D material research. The layers of TMD are bound together by weak van der Waals (vdW) forces, and various MX2 materials can host additional ions within the vdW gaps through the intercalation process. Our study focuses on the magnetic properties of the 3d transition-metal-intercalated TMD.

We fabricated thin films of Cr-intercalated TaSe2 by molecular-beam epitaxy (MBE). Cr1/4TaSe2 with the 2×2 superstructure could be grown by MBE. The post-growth annealing in ultrahigh vacuum enabled modulation of the superstructure pattern into √3×√3, which turned out to exhibit in-plane ferromagnetism with the finite out-of-plane component as revealed by the anomalous-Hall effect measurements. We also observed unusual magneto-transport properties characterized with the positive component with the out-of-plane fields. In the presentation, we will show those experimental results in detail, and discuss the similarities and differences between CrxTaSe2 and CrxNbSe2.
発表言語 日本語
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