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Electronic properties of 3d transition metal dihalide monolayers predicted by DFT methods: Is there a pattern or are the results random?

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Journal of the Chinese Chemical Society 2023年第3期70卷 359-371页

作者： Chiu, Cheng-chau Wang, Chung-Yu Huang, Bo-Jie Kuo, Jer-Lai Department of Chemistry National Sun Yat-sen University Kaohsiung Taiwan Center for Theoretical and Computational Physics National Sun Yat-sen University Kaohsiung Taiwan Green Hydrogen Research Center National Sun Yat-sen University Kaohsiung Taiwan Institute of Atomic and Molecular Sciences Academia Sinica Taipei Taiwan Molecular Science and Technology Program Taiwan International Graduate Program Academia Sinica Taipei Taiwan Department of Chemistry National Tsing Hua University Hsinchu Taiwan International Graduate Program of Molecular Science and Technology (NTU-MST) National Taiwan University Taipei Taiwan

We use periodic DFT calculations at LDA and PBE level to investigate 3d transition metal dihalide (TMDH) monolayers in H- and T-phase. By analyzing the phonon dispersion, we have obtained a rough overview which combinations may form stable structures. We have focused on identifying and explaining trends in the predicted electronic properties. Although their geometric structures are simple, the associated electronic and magnetic properties are not as easy to understand. At first glance, it seems that there is no clear trend, as even isovalence-electronic TMDH monolayers formed from the same metal but different halides can feature different magnetic moments. The identification of potential trends is further complicated by the fact that for a significant number of species, LDA results and PBE results predict different ground-state electronic structures. By rigorously analyzing the potential energy surfaces associated with different magnetic moments, we could show that the apparent inconsistencies can be easily understood as a result of the differences in the relative energy between electronic states of different magnetic moments. We further show that the trends in the band gaps can be easily rationalized by an electron counting rule based on simple symmetry arguments. © 2022 Chemical Society Located in Taipei and Wiley-VCH GmbH.

关键词： 2D materials DFT electronic structure monolayer spin transition metal dihalides

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An inverted-pendulum thrust stand for high-power electric thrusters

An inverted-pendulum thrust stand for high-power electric th...

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AIAA/ASME/SAE/ASEE 42nd Joint Propulsion Conference

作者： Kodys, A.D. Murray, R. Cassady, L. Choueiri, E.Y. Electric Propulsion and Plasma Dynamics Laboratory Mechanical and Aerospace Engineering Department Princeton University Princeton NJ 08511 United States NASA Graduate Student Research Program Princeton Plasma Science and Technology Program United States EPPDyL United States Applied Physics Group United States AIAA United States

ISBN: (纸本)1563478188

The inverted-pendulum method of thrust measurement for high-power electric thrusters is described analytically and experimentally. Two sources of uncertainty in the thrust measurements are investigated: those due to changes in the sensitivity of the inverted pendulum and those due to tare forces resulting from thermal stresses and electromagnetic forces acting on the flexural elements. An idealized analytical model shows that changes in sensitivity occur due to changes in the mass loading of the inverted pendulum and the temperature of the flexure elements. The sensitivity can be increased only at the expense of more stringent requirements on mass loading and thermal control. The results of the model are validated with measurements made using a carefully calibrated inverted pendulum thrust stand having several advantageous design features including gallium pots for current conduction, an optical two-axis displacement sensor, and careful consideration of flexure shape and cooling requirements. The sensitivity is shown to be constant over a wide range of operating conditions. Measurements show that thermal drifts of the stand are linear on the time scale of the thrust measurements and are less than 0.6% of the expected thrust. The thrust stand operation was demonstrated during experiments with a 30-kW lithium-fed applied-field magnetoplasmadynamic thruster. Under nominal conditions (400 A, 0.1 T, 17.5 mg/s) the thermal and electromagnetic tare forces were measured at less than 9% of the thrust and the total thrust uncertainty at ≤ 10% of the thrust.

关键词： Electric propulsion

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Self-Expansion Based Multi-Patterning for 2D Materials Fabrication beyond the Lithographical Limit

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Small 2024年第22期20卷 2311209-2311209页

作者： Borhade, Poonam Subhash Chen, Tawat Chen, Ding-Rui Chen, Yu-Xiang Yao, Yu-Chi Yen, Zhi-Long Tsai, Chun Hsiung Hsieh, Ya-Ping Hofmann, Mario Department of Physics National Taiwan University Taipei10617 Taiwan Nano Science and Technology Program Taiwan International Graduate Program Academia Sinica Taipei10617 Taiwan Institute of Atomic and Molecular Sciences Academia Sinica Taipei10617 Taiwan Hsinchu30092 Taiwan International Graduate Program of Molecular Science and Technology National Taiwan University Taipei10617 Taiwan Molecular Science and Technology Program Taiwan International Graduate Program Academia Sinica Taipei10617 Taiwan

Two-dimensional (2D) materials are promising successors for silicon transistor channels in ultimately scaled devices, necessitating significant research efforts to study their behavior at nanoscopic length scales. Unfortunately, current research has limited itself to direct patterning approaches, which limit the achievable resolution to the diffraction limit and introduce unwanted defects into the 2D material. The potential of multi-patterning to fabricate 2D materials features with unprecedented precision and low complexity at large scale is demonstrated here. By combining lithographic patterning of a mandrel and bottom-up self-expansion, this approach enables pattern resolution one order of magnitude below the lithographical resolution. In-depth characterization of the self-expansion double patterning (SEDP) process reveals the ability to manipulate the critical dimension with nanometer precision through a self-limiting and temperature-controlled oxidation process. These results indicate that the SEDP process can regain the quality and morphology of the 2D material, as shown by high-resolution microscopy and optical spectroscopy. This approach is shown to open up new avenues for research into high-performance, ultra-scaled 2D materials devices for future electronics. © 2023 Wiley-VCH GmbH.

关键词： Expansion

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Nonlinear Twistronics for EM Waves

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IEEE Transactions on Antennas and Propagation 2025年

作者： Valagiannopoulos, Constantinos Alu, Andrea National Technical University of Athens School of Electrical and Computer Engineering Athens15780 Greece City University of New York Photonics Initiative Advanced Science Research Center New YorkNY10031 United States City College of The City University of New York Department of Electrical Engineering New YorkNY10031 United States City University of New York Physics Program Graduate Center New YorkNY10016 United States

The electromagnetic (EM) interaction between two anisotropic nonlinear metasurfaces, under arbitrary rotations of their optical axes, is rigorously studied. Multistability conditions with respect to rotation angles between the two surfaces are determined and explored. The examined setup demonstrates opportunities for memory and storage since these in-plane rotations may act as continuous information carriers. The abrupt transitions of the system response, from one solution branch to the other, materialize the concept of twistronics engineering in the classical EM regime, sensitive to small angular changes. These findings can enhance the design of several photonic devices from ultra-sharp sensors and switches to analog information processors and optical memory elements. © 1963-2012 IEEE.

关键词： Optical bistability

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New type of frequency standard transitions realized by comb laser

New type of frequency standard transitions realized by comb ...

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CLEO: science and Innovations, S and I 2022

作者： Chen, Bo-Wei Liu, Tze-Wei Yu, Hsin-Hung Cheng, Wang-Yau Department of Physics National Central University Taoyuan32001 Taiwan Molecular Sciences and Technology Taiwan International Graduate Program Academia Sinica National Central University Taipei Taiwan Institute of Atomic and Molecular Science Academia Sinica Taipei11529 Taiwan

The clock transitions recommended by BIPM are never realized by a femtosecond comb laser. In this report, we recommend two comb-laser-based stepwise transitions resolved simultaneously from rubidium and cesium atom. &... 详细信息

ISBN: (纸本)9781557528209

关键词： Frequency standards

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Detection of Femtomolar Amyloid-β Peptides for Early-Stage Identification of Alzheimer’s Amyloid-β Aggregation with Functionalized Gold Nanoparticles

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ACS Applied Materials and Interfaces 2024年第3期16卷 3819-3828页

作者： Chang, Yu-Jen Chien, Yi-Hsin Chang, Chieh-Chun Wang, Pei-Ning Chen, Yun-Ru Chang, Yun-Chorng Genomics Research Center Academia Sinica Taipei115 Taiwan Taiwan International Graduate Program in Interdisciplinary Neuroscience National Taiwan University and Academia Sinica Taipei115 Taiwan Research Center for Applied Sciences Academia Sinica Taipei115 Taiwan Department of Physics National Taiwan University Taipei106 Taiwan Nano Science and Technology Program Taiwan International Graduate Program Academia Sinica and National Taiwan University Taipei115 Taiwan Brain Research Center National Yang Ming Chiao Tung University Taipei112 Taiwan Division of General Neurology Department of Neurological Institute Taipei Veterans General Hospital Taipei112 Taiwan

Progressive amyloid-β (Aβ) fibrillar aggregates have long been considered as the pathogenesis of Alzheimer’s disease (AD). Biocompatible and stable cysteine-Aβ peptide-conjugated gold nanoparticles (Cys-Aβ@AuNP) are demonstrated as suitable materials for detecting subfemtomolar Aβ peptides in human plasma. Incubation with Aβ peptides causes the Cys-Aβ@AuNP to aggregate and changes its absorption spectra. The spectral change is especially apparent and noticeable when detecting subfemtomolar Aβ peptides, and the aggregates contain only two or three AuNPs. Cys-Aβ@AuNP can also be used to identify early-stage Aβ oligomerization, which is not possible using the conventional method, in which the fluorescence of thioflavin-T is measured. The ability to detect Aβ oligomerization can facilitate therapeutics for AD. In addition, the binding of Aβ peptides by Cys-Aβ@AuNP in combination with centrifugation redirects the conventional Aβ aggregation pathway and can effectively inhibit the formation of toxic Aβ oligomers or fibrils. Therefore, the proposed Cys-Aβ@AuNP can also be used to develop effective therapeutic agents to inhibit Aβ aggregation. The results obtained in this study are expected to open revolutionary ways to both detect and inhibit Aβ aggregation at an early stage. © 2024 American Chemical Society

关键词： Oligomers

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Electron Acceleration in Carbon Nanotubes

arXiv

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arXiv 2025年

作者： Bonţoiu, Cristian Bonatto, Alexandre Apsimon, Öznur Bandiera, Laura Cavoto, Gianluca Drebot, Illya Gatti, Giancarlo Giner-Navarro, Jorge Lei, Bifeng Martín-Luna, Pablo Rago, Ilaria Pérez, Juan Rodríguez Nunes, Bruno Silveira Sytov, Alexei Valagiannopoulos, Costas Welsch, Carsten P. Xia, Guoxing Resta-López, Javier Department of Physics University of Liverpool Oxford Street LiverpoolL69 7ZE United Kingdom Graduate Program in Information Technology and Healthcare Management the Beam Physics Group Federal University of Health Sciences of Porto Alegre RS Porto Alegre90050-170 Brazil Department of Physics and Astronomy University of Manchester Oxford Road ManchesterM13 9PL United Kingdom Cockroft Institute Keckwick Lane Daresbury WarringtonWA4 4AD United Kingdom INFN Sezione di Ferrara Via Saragat 1 Ferrara44122 Italy Dipartimento di Fisica Sapienza Università di Roma Piazzale Aldo Moro 2 Roma00185 Italy INFN Sezione di Roma Piazzale Aldo Moro 2 Rome00185 Italy INFN Sezione di Milano Via G. Celoria 16 Milano20133 Italy Centro de Láseres Pulsados Building M5 Science Park Calle Adaja 8 Salamanca Villamayor37185 Spain Universidad de Valencia Paterna46071 Spain Universidad de Valencia CSIC Paterna46980 Spain Nuclear and Energy Research Institute IPEN–CNEN SP São Paulo Brazil National Technical University of Athens School of Electrical and Computer Engineering Zografou157 73 Greece Departamento de Física Aplicada y Electromagnetismo Universidad de Valencia Burjassot46100 Spain

Laser wakefield acceleration (LWFA) may achieve TeV/m gradients using high-density solid-state plasmas as accelerating media. However, the application of bulk solid materials requires attosecond laser pulses, such as X-ray lasers, to drive wakefields at these high densities. Additionally, the short wakefield wavelengths associated with solid-state plasmas greatly limit the accelerating length. An alternative approach employs 2D carbon-based nanomaterials, like graphene or carbon nanotubes (CNTs), configured into structured targets. These nanostructures are designed with voids or low-density regions to effectively reduce the overall plasma density. This reduction enables the use of longer-wavelength lasers and also extends the plasma wavelength and the acceleration length. In this study, we present, to our knowledge, the first numerical demonstration of electron acceleration via self-injection into a wakefield bubble driven by an infrared laser pulse in structured CNT targets, similar to the behavior observed in gaseous plasmas for LWFA in the nonlinear (or bubble) regime. Using the PIConGPU code, bundles of CNTs are modeled in a 3D geometry as 25 nm-thick carbon tubes with an initial density of 1022 cm−3. The carbon plasma is ionized by a three-cycle, 800 nm wavelength laser pulse with a peak intensity of 1021 W cm−2, achieving an effective plasma density of 1020 cm−3. The same laser also drives the wakefield bubble, responsible for the electron self-injection and acceleration. Simulation results indicate that fs-long electron bunches with hundreds of pC charge can be self-injected and accelerated at gradients exceeding 1 TeV/m. Both charge and accelerating gradient figures are unprecedented when compared with LWFA in gaseous plasma. © 2025, CC BY-NC-ND.

关键词： X ray lasers

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Temperature-dependence of hypersound dynamics in SrRuO3/SrTiO3 heterostructures

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Physical Review B 2018年第6期98卷 064308-064308页

作者： Chi-Yuan Yang (楊濟源) Kung-Hsuan Lin (林宮玄) Department of Physics National Taiwan University Taipei 10617 Taiwan Nano-Science and Technology Program Taiwan International Graduate Program Academia Sinica Taipei 11529 Taiwan Institute of Physics Academia Sinica Taipei 11529 Taiwan

We studied GHz hypersound in heterostructures of SrRuO3 (SRO) and SrTiO3 (STO) by using femtosecond pulses with fluence as low as several tens of μJ/cm2. We found that the efficiency of generating hypersound in SRO, through thermal expansion, is linear up to optical fluence of a few mJ/cm2. We further investigated the propagation of acoustic pulses in the STO substrate. The acoustic properties of STO dramatically changed around the temperature of structural transition (105 K) because the generated hypersound was coupled to the softening mode. Nevertheless, our experimental results revealed that the quadratic frequency dependence of acoustic attenuation in STO, predicted by the mode-coupling theory, breaks down at tens of GHz. Finally, the refractive index of STO was experimentally obtained between 365 and 400 nm, for which there was disagreement in previous results.

关键词： Multiferroics Multilayer thin films Perovskites Brillouin scattering & spectroscopy Femtosecond laser irradiation Femtosecond laser spectroscopy Ultrafast pump-probe spectroscopy

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Visible blind, wearable, and omnidirectional near infrared photodetector: A filterless approach

Visible blind, wearable, and omnidirectional near infrared p...

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Frontiers in Optics, FIO 2019 - Part of Frontiers in Optics + Laser science APS/DLS

作者： Kataria, Monika Wang, Wei-Hua Chen, Yang-Fang Institute of Atomic and Molecular Sciences Academia Sinica Taipei115 Taiwan Department of Physics National Central University Chung-Li320 Taiwan Molecular Science and Technology Program Taiwan International Graduate Program Institute of Atomic and Molecular Sciences Academia Sinica Taipei115 Taiwan Department of Physics National Taiwan University Taipei106 Taiwan Advanced Research Centre Green Materials Science and Technology National Taiwan University Taipei10617 Taiwan

ISBN: (纸本)9781943580675

We present a highly sensitive, filtlerless, visible blind, omnidirectional and wearable near infrared photodetector suitable for next generation of wearable technologies. Here, the hybrid device constituents include lanthanides doped upconversion nanoparticles, graphene and micro-pyramidical poly(dimethylsiloxane) film. This hybrid device exhibits ultra-high responsivity of ~ 800 AW-1 at VDS = 1 V under 0.07 µW of 980 nm laser illumination. The novel design of the device makes it user friendly, light weight, durable and transparent. © OSA 2019. The Author(s).

关键词： Wearable technology

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Spin-orbit-locked hyperbolic polariton vortices carrying reconfigurable topological charges

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eLight 2022年第1期2卷 143-153页

作者： Mingsong Wang Guangwei Hu Saroj Chand Michele Cotrufo Yohannes Abate Kenji Watanabe Takashi Taniguchi Gabriele Grosso Cheng‑Wei Qiu Andrea Alù Photonics Initiative Advanced Science Research CenterCity University of New YorkNew York CityNY 10031USA Department of Electrical and Computer Engineering National University of SingaporeSingapore 116083Singapore Department of Physics and Astronomy The University of GeorgiaAthensGA 30602USA Research Center for Functional Materials National Institute for Materials ScienceTsukubaIbaraki 305‑0044Japan International Center for Materials Nanoarchitectonics National Institute for Materials ScienceTsukubaIbaraki 305‑0044Japan Physics Program Graduate CenterCity University of New YorkNew YorkNY 10016USA

The topological features of optical vortices have been opening opportunities for free-space and on-chip photonic technologies,e.g.,for multiplexed optical communications and robust information *** a parallel but disjoint effort,polar anisotropic van der Waals nanomaterials supporting hyperbolic phonon polaritons(HP2s)have been leveraged to drastically boost light-matter *** far HP2 studies have been mainly focusing on the control of their amplitude and scale *** we report the generation and observation of mid-infrared hyperbolic polariton vortices(HP2Vs)associated with reconfigurable topological ***-shaped gold disks coated with a flake of hexagonal boron nitride are exploited to tailor spin-orbit interactions and realise deeply subwavelength *** complex interplay between excitation spin,spiral geometry and HP2 dispersion enables robust reconfigurability of the associated topological *** results reveal unique opportunities to extend the application of HP2s into topological photonics,quantum information processing by integrating these phenomena with single-photon emitters,robust on-chip optical applications,sensing and nanoparticle manipulation.

关键词： Hyperbolic polariton vortex Light-matter interactions Spin-orbit interaction Topological charge Reconfigurability

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