Phonon dispersion relations characterize collective lattice vibrations in crystalline solids and provide fundamental insight into their vibrational properties. Within the harmonic approximation, which represents the quadratic expansion of the lattice potential energy around equilibrium, phonon dispersions can be obtained and are widely used to analyze basic lattice dynamical...
Thermoelectric transport provides a sensitive probe of carrier type and the energy-dependent electronic structure near the Fermi level, while also offering a practical route toward energy harvesting and self-powered thermal sensing. Here, we present our recent progress in graphene-based thermoelectric and field-effect devices fabricated on plastic substrates. By combining CVD graphene with...
Microplastic fragments, such as polypropylene (PP), polyethylene (PE), and polystyrene (PS), persist in aquatic environments, where they can act as carriers of chemical contaminants while also raising concerns about their direct biological effects. Microplastics have been detected throughout the food chain and even within human tissues, making their reliable identification at trace levels an...
LiNbO3 is a widely used nonlinear optical material for photonic and quantum devices, where Li vacancy critically affects optical loss and photorefractive degradation under high-power operation. However, its quantitative evaluation remains challenging due to the low sensitivity of X-ray-based techniques to light elements. In this work, we systematically investigate the composition-dependent...
The SND@LHC experiment has been performed to detect high energy neutrinos produced in the forward direction at the LHC from 2022. This experiment can cover the unexplored ranges of energy (100 GeV-TeV) and pseudo-rapidity (7.2-8.4), in which a large fraction of neutrinos originate from charmed hadrons decays. The SND@LHC uses Emulsion Cloud Chamber (ECC) as target and tracking detector,...
Controlling the Fermi level is essential for tailoring the electronic properties of semiconductors. Here, we investigate two routes of chemical doping and defect control using scanning tunneling microscopy and spectroscopy. For V-doped MoSe$_2$, we study how substitutional V atoms influence its electronic structure. Although STM primarily probes the top Se layer and the dopants are not...
The Co–Zr binary system contains several superconducting intermetallic compounds, including CoZr₂ and CoZr₃, which exhibit critical temperatures ($T_c$) of approximately 5.2 K and 3.4 K, respectively [1, 2]. In this study, we investigate superconducting properties of polycrystalline CoZr₂-based compounds synthesized by self-propagating high-temperature synthesis (SHS) [3], which has rarely...
물질의 전자 상태를 분석하기 위해 Angle-Resolved Photoemission Spectroscopy (ARPES)를 이용할 수 있지만, 일반적인 ARPES는 광원의 크기 제한으로 인해 수백 마이크로미터 이상의 균일한 시료가 필요하다. 이러한 한계를 극복하기 위해 Spatially-resolved ARPES가 활용되고 있으나 작은 크기의 저차원 반데르발스 물질의 전자구조를 정확하게 측정하기 위해서는 오염이 없는 깨끗한 표면을 확보하는 것이 필수적이다. 기존의 화학 세척, Plasma Etching 및 Annealing 공정은 잔류 오염물 제거 효율 및, 시료 손상 측면에서 한계를 가진다. 본 연구에서는 화학 세척만 수행한 시료와 Atomic Force Microscopy(AFM)...
회색비소(Gray aresnic)은 반 데르발스 힘으로 결합된 층상구조를 가진 위상물질 중 하나로써 위상학적으로 구분되는 표면 전자밴드를 가지는 물질이다.[1] 이전 실험 결과에서 각각 다른 온도에서 회색비소의 전자구조를 ARPES(Angle Resolved PhotoEmission Spectroscopy)로 관찰해보았을 때, 전체적인 밴드 구조가 서로 다른 Binding Energy에 위치함을 확인할 수 있었다.이 현상에 대한 원인으로 이전에 준금속에서 온도변화에 따른 화적 포텐셜 변화가 전체적인 밴드구조 이동에 대한 원인이라고 밝히는 논문을 참고하여[2][3] 회색비소에서 발생한 현상 또한 화학적 포텐셜 변화 떄문이라고 가정했다.
가설을 검증하기 위해 10K 에서 90K 까지 온도를 올리고 다시...
