応用物理学輪講 I
12月3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
2021年12月3日(金)16:50〜

Aグループ

座長
半田 光
指導
教員名
高橋 陽太郎 准教授
座長
福田 大地
指導
教員名
鹿野田 一司 教授
発表者名 濱尾 智
指導教員名 石坂 香子 教授
発表題目(英語) Investigation of band structures in Cr intercalated NbSe2 by angle-resolved photoemission spectroscopy
要旨(英語)  Transition metal dichalcogenides (TMDs) are van der Waals (vdW) layered materials and have attracted attention as a group of materials that exhibit a variety of physical properties due to their diverse constituent elements and crystal polymorphism. It is also known that the intercalation of alkali metal or transition metal atoms in the van der Waals gap leads to the appearance of physical properties different from those of the parent material. In particular, it has been recently reported that intercalation of 3d transition metal atoms can produce not only various magnetic properties but also topological semimetallic structures [1], and experimental verification is required.
 In this presentation, I will explain the methods of angle-resolved photoemission spectroscopy (ARPES) and sample fabrication by molecular beam epitaxy (MBE). Next, I will present the result of ARPES experiments on Cr1/3NbSe2 thin films fabricated by MBE. In this experiment, we clarified the three-dimensional band structure in the 10-layer thick Cr1/3NbSe2 thin film, and found the band crossing which indicates the topological feature. Finally, I will introduce the layer number dependent study of Cr1/3NbSe2 band structures, which we are working on as a future issue.

[1] T. Inoshita, et al., Phys. Rev. B 100, 121112 (2019).
発表言語 日本語
発表者名 吹上 義樹
指導教員名 長谷川 幸雄 教授
発表題目(英語) Measurement of Spin Dynamics by Scanning Tunneling Microscopy
要旨(英語)  Scanning Tunneling Microscopy (STM) has made a significant contribution to nanoscale condensed matter physics. STM utilizes the electron tunneling effect between the sample surface and a sharp metal tip. Because the tunneling probability decreases dramatically with atomic-scale distance, STM provides us with surface images in an atomically high spatial resolution. STM can also bring us electronic properties of local surface area through the tunneling spectroscopy, which probes the local density of states below the probe tip.
 STM can also probe the static magnetic properties by using a magnetic tip by tunnel magnetoresistance (spin-polarized STM, SP-STM). Recently, a new method to probe dynamics of magnetic properties and spins was developed through the introduction of the technique of electron spin resonance (ESR) into STM and attracted significant attention in the community.
 In this presentation, I will introduce STM and its techniques for probing static and dynamical magnetic properties.
発表言語 日本語
発表者名 藤原 孝輔
指導教員名 森本 高裕 准教授
発表題目(英語) Thermal Hall effect in a frustrated honeycomb magnet without DM interaction
要旨(英語)  We study the thermal responses of magnons in a honeycomb lattice with frustration. While most of the previous studies on transverse thermal responses in magnets consider the effect of DM interaction, we propose that the nonzero thermal Hall effect arises without DM interaction once we incorporate frustration with the next nearest neighbor coupling and asymmetry between sublattices. We determine spiral spin configurations that minimize the total energy classically and derive a magnon Hamiltonian from the obtained configuration using Holstein-Primakov transformation. We compute Berry curvature that characterizes a nontrivial geometry of the magnon states and discuss the thermal Hall effect that originates from such nontrivial geometry.
発表言語 日本語

Bグループ

座長
馬場 正太郎
指導
教員名
中村 泰信 教授
座長
早野 陽紀
指導
教員名
古川 亮 准教授
発表者名 藤原 心
指導教員名 芦原 聡 教授
発表題目(英語) Investigation of a new method for molecular spectroscopy with mid-infrared lasers
要旨(英語)  Mid-infrared light resonates with the vibration-rotation transitions of molecules and has a characteristic absorption spectrum. Since molecules can be identified by analyzing this spectrum, mid-infrared region is called the molecular fingerprints. In this study, I propose a new method that utilizes the features of a short-pulse broadband laser.
 In this presentation, I will explain the method and then show you the results of numerical calculations for the design of the apparatus.
発表言語 日本語
発表者名 古谷 登
指導教員名 木村 隆志 准教授
発表題目(英語) Development of Single-Shot X-ray Microspectroscopic Imaging using a Multi-Aperture Grating
要旨(英語)  X-ray microscopes have a higher resolution than visible light microscopes due to the short wavelength of X-rays. The elements and chemical states of samples can be determined by spectroscopic techniques, which analyse the absorption spectrum of samples with X-rays. We use synchrotron radiation as a light source for X-ray microspectroscopic imaging because of its wavelength selectivity. However, spectroscopic measurements require long measurement duration while changing the wavelength of X-rays. In addition, measuring the spatial distribution of elements and chemical states requires the scanning operation of the sample, which requires vast measurement time and results in damaging the samples. We propose a newly-designed diffraction grating, which enables microspectroscopic imaging with a single-pulse measurement (~ a few fs). Optimizing the shape and interval of the grating with a wave-optical simulation, I am investigating the possible design of a grating with high spatial and energy resolution. In this presentation, I will also introduce the sample which I prepared to evaluate the performance of the proposed X-ray microspectroscopic imaging.
発表言語 日本語
発表者名 松澤 創一郎
指導教員名 為ヶ井 強 准教授
発表題目(英語) Characterizations of Anisotropic Superconductivity in Misfit Layered compounds
要旨(英語) Misfit layered compounds (MLCs) are layered chalcogenides with incommensurate stacking of two sublattices with different symmetries and have been studied for decades due to very unique structures and various interesting physical properties. The chemical formula of MLCs is generally represented as (MX)1+x(TX2)n, where M is Sn, Sb, Pb, Bi, or rare earth metals, T is transition metals, and X is S or Se. The structure of MLCs is composed of van-der-Waals coupling of two sublattice layers, i.e., rocksalt-type monochalcogenide MX and trigonal-prisms dichalcogenide TX2.
 Among various MLCs family, (BiSe)1.10NbSe2 is known to show superconductivity with the critical temperature Tc of 2.3 ~ 3.3K. Recently, there are some reports claiming that the superconductivity of NbxBi2Se3, a material that Nb atoms are doped into a topological insulator Bi2Se3, is identical to the misfit phase (BiSe)1.10NbSe2. However, the origin of NbxBi2Se3 remains still controversial.
 In this presentation, we report the growth of single crystals of (BiSe)1+δNbSe2 with different δ and its anisotropy both out-of-plane and in-plane directions by the upper critical field measurements.
発表言語 日本語