応用物理学輪講 I
11月28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
2025年11月28日(金) 16：50～18：50

Aグループ

座長
太附　孝輔
指導
教員名
森本　高裕　准教授
座長
寺河　俊宏
指導
教員名
Max Hirschberger 准教授
発表者名 西田　大晟
指導教員名 森本　高裕　准教授
発表題目（英語） Brillouin zone folding method for superconducting multilayer systems
要旨（英語） Van der Waals (vdW) heterostructures, such as twisted bilayer graphene, have recently emerged as a material platform for discovering novel quantum phenomena, as their electronic states can be significantly tuned through the control of layer stacking and twist angles.

Meanwhile, multilayer thin films generally lack translational symmetry, and therefore Bloch’s theorem cannot be applied. As a result, theoretical analysis based on momentum-space band theory becomes difficult.

In this presentation, I will introduce the Brillouin zone folding method, a momentum-space approach that can be applied even to non-periodic multilayer thin films, and its extension to superconducting states.
発表言語 日本語
発表者名 花澤　萌子
指導教員名 芦原　聡　教授
発表題目（英語） Broadband and high-power infrared laser system for background-free vibrational spectroscopy
要旨（英語） In infrared spectroscopy, when light of various frequencies passes through a sample, only the light whose frequency matches one of the molecular vibrational frequencies is absorbed, producing an absorption spectrum. In conventional method, the detection limit was influenced by the ratio between the maximum and minimum detectable signal because absorption by the sample is observed as a decrease in transmittance. Here, we have developed “background-free spectroscopy” that detects only the molecular absorption as a peak via destructive interference, and we have successfully achieved highly sensitive measurements in the 2 μm region. In this method, increasing the output of the light source enables even higher sensitivity. The ultimate purpose of this study is to perform background-free vibrational spectroscopy in the 3–10 μm range, which is commonly used for molecular identification. To achieve this goal, I aim to generate highly spatially coherent, broadband and high-power light using a system composed of an infrared mode-locked laser based on a Cr:ZnS crystal and an optical parametric oscillator (OPO).
発表言語 日本語
発表者名 林　隼介
指導教員名 石坂　香子　教授
発表題目（英語） Development of precession Lorentz electron microscopy toward visualization of emergent magnetism
要旨（英語） Emergent magnetic nanotextures such as skyrmions have attracted considerable interest for spintronic applications. Lorentz transmission electron microscopy (LTEM) is widely used for high-resolution (~nm) imaging of magnetic textures, including in situ observations under external stimuli such as electric currents and strain. Moreover, recently developed ultrafast TEM (UTEM), which is based on the pump–probe scheme, has enabled investigations of nonequilibrium spin-texture dynamics on the nanosecond timescale. However, magnetic contrast is often obscured by diffraction contrast originating from crystal inhomogeneity, which becomes particularly problematic for dynamic observations where magnetic textures evolve nonlocally in time and space.In this study, we introduce the precession method into LTEM to suppress diffraction contrast. By varying the incident beam angle in a precessional manner and averaging images obtained under different diffraction conditions, diffraction contrast is strongly reduced while magnetic contrast remains largely unaffected. This approach is expected to enable continuous tracking of the motion of magnetic textures on the micrometer scale, as well as the elucidation of nonequilibrium dynamics involving large temporal variations, which have been difficult to investigate using conventional methods.
発表言語 日本語

Bグループ

座長
寺薗　隆之
指導
教員名
小林　洋平　教授
発表者名 原多　己暢
指導教員名 齊藤　英治　教授・山本　浩史　委嘱教授
発表題目（英語） Chirality induced spin selectivity in donor-acceptor molecules
要旨（英語） Around 2000, a phenomena called chirality-induced spin selectivity(CISS) effect was reported. Electric current passing through a chiral material exhibits large spin polarization, depending on the handedness of the material and the direction of the current. Although CISS effect has been reported in a lot of materials, it is difficult to distinguish CISS effect from the contribution of the substrate. Recently, CISS effect in isolated donor-acceptor molecules was observed, which will broaden our perspective about CISS effect.

In the first half of my presentation, I will briefly introduce several notable papers about CISS effect from early work to recent papers. In second half, I will explain the basic physics and experiments about CISS effect in donor-acceptor molecules.
発表言語 日本語
発表者名 中嶋　陽太
指導教員名 川﨑　雅司　教授
発表題目（英語） Topological Hall Effect at Pyrochlore-Type Oxide Thin Film Interfaces and Its Analysis
要旨（英語） A non-coplanar spin texture generates a virtual magnetic field, known as an emergent magnetic field, which is proportional to the solid angle subtended by the spins. This field, much like a conventional magnetic field, deflects the trajectory of electrons, giving rise to a phenomenon known as the Topological Hall Effect. While this effect has conventionally been observed only in magnetic conductors, which poses significant limitations on material selection, our study successfully observes this phenomenon at the interface of an oxide heterostructure composed of a non-magnetic conductor and a magnetic insulator. In addition to providing a quantitative analysis of this Hall effect, by examining the thickness dependence of the conducting layer, we believe we have successfully captured the propagation behavior of the emergent magnetic field from the interface.
発表言語 日本語
発表者名 平野　沙織
指導教員名 十倉　好紀　卓越教授
発表題目（英語） Fabrication of an artificial polar magnetic Weyl semimetal via superlattice engineering and its Emergent electromagnetic inductance
要旨（英語） The magnetic topological insulator Cr-doped (Bi,Sb)₂Te₃, known for the first observation of the quantized anomalous Hall effect, has recently been shown to undergo a phase transition into a ferromagnetic Weyl semimetal in the high-Cr-doping regime. In this study, we further engineer the thin-film structure into a tricolor superlattice to introduce polarity into the system, aiming to realize a polar magnetic Weyl semimetal and explore emergent quantum phenomena.
In this presentation, I will discuss two main topics. First, I will present experimental results that both support and challenge the realization of a polar magnetic Weyl semimetal in the tricolor superlattice structure. Second, I will report on the current progress in investigating emergent electromagnetic inductance, an effect attributed to superlattice-induced virtual magnetic and electric fields within the material.
発表言語 日本語
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