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Mechanically reprogrammable Pancharatnam-Berry metasurface for microwaves

Advanced Photonics 2022年第1期4卷 69-79页

作者： Quan Xu Xiaoqiang Su Xueqian Zhang Lijuan Dong Lifeng Liu Yunlong Shi Qiu Wang Ming Kang Andrea Alù Shuang Zhang Jiaguang Han Weili Zhang Tianjin University Center for Terahertz Waves and College of Precision Instrument and Optoelectronics EngineeringKey Laboratory of Optoelectronic Information Technology(Ministry of Education of China)TianjinChina Shanxi Datong University Institute of Solid State Physics and College of Physics and Electronic ScienceShanxi Province Key Laboratory of Microstructure Electromagnetic Functional MaterialsDatongChina Wuhan University of Technology School of Information EngineeringWuhanChina Tianjin Normal University College of Physics and Materials ScienceTianjinChina City University of New York Advanced Science Research CenterPhotonics InitiativeNew YorkUnited States City University of New York Graduate CenterPhysics ProgramNew YorkUnited States University of Hong Kong Faculty of ScienceDepartment of PhysicsHong KongChina University of Hong Kong Department of Electrical and Electronic EngineeringHong KongChina Guilin University of Electronic Technology Guangxi Key Laboratory of Optoelectronic Information ProcessingSchool of Optoelectronic EngineeringGuilinChina Oklahoma State University School of Electrical and Computer EngineeringStillwaterOklahomaUnited States

Metasurfaces have enabled the realization of several optical functionalities over an ultrathin platform,fostering the exciting field of flat *** metasurfaces are achieved by arranging a layout of static meta-atoms to imprint a desired operation on the impinging wavefront,but their functionality cannot be *** and programmability of metasurfaces are the next important step to broaden their impact,adding customized on-demand functionality in which each meta-atom can be individually *** demonstrate a mechanical metasurface platform with controllable rotation at the meta-atom level,which can implement continuous Pancharatnam–Berry phase control of circularly polarized *** the proof-of-concept experiments,we demonstrate metalensing,focused vortex beam generation,and holographic imaging in the same metasurface template,exhibiting versatility and superior *** dynamic control of electromagnetic waves using a single,low-cost metasurface paves an avenue towards practical applications,driving the field of reprogrammable intelligent metasurfaces for a variety of applications.

关键词： reprogrammable metasurfaces Pancharatnam-Berry phase mechanical metasurfaces microwaves

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Valley lifetimes of conduction band electrons in monolayer WSe2

arXiv

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arXiv 2020年

作者： Ersfeld, Manfred Volmer, Frank Rathmann, Lars Kotewitz, Luca Heithoff, Maximilian Lohmann, Mark Yang, Bowen Watanabe, Kenji Taniguchi, Takashi Bartels, Ludwig Shi, Jing Stampfer, Christoph Beschoten, Bernd 2nd Institute of Physics JARA-FIT RWTH Aachen University Aachen52074 Germany Department of Physics and Astronomy University of California RiversideCA92521 United States Department of Chemistry and Materials Science & Engineering Program University of California RiversideCA92521 United States Research Center for Functional Materials National Institute for Materials Science 1-1 Namiki Tsukuba Ibaraki305-0044 Japan International Center for Materials Nanoarchitectonics National Institute for Materials Science 1-1 Namiki Tsukuba Ibaraki305-0044 Japan Forschungszentrum Jülich Jülich52425 Germany

One of the main tasks in the investigation of 2-dimensional transition metal dichalcogenides is the determination of valley lifetimes. In this work, we combine time-resolved Kerr rotation with electrical transport measurements to explore the gate-dependent valley lifetimes of free conduction band electrons of monolayer WSe2. When tuning the Fermi energy into the conduction band we observe a strong decrease of the respective valley lifetimes which is consistent with both spin-orbit and electron-phonon scattering. We explain the formation of a valley polarization by the scattering of optically excited valley polarized bright trions into dark states by intervalley scattering. Furthermore, we show that the conventional time-resolved Kerr rotation measurement scheme has to be modified to account for photo-induced gate screening effects. Disregarding this adaptation can lead to erroneous conclusions drawn from gate-dependent optical measurements and can completely mask the true gate-dependent valley dynamics. Copyright © 2020, The Authors. All rights reserved.

关键词： Landforms

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Adsorption efficiency of methylene blue from aqueous solution with amine-functionalized mesoporous silica nanospheres by co-condensation biphasic synthesis: adsorption condition and equilibrium studies

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materials Today: Proceedings 2018年第6期5卷 14079-14085页

作者： R. Chueachot S. Wongkhueng K. Khankam A. Lakrathok T. Kaewnon W.T. Naowanon S. Amnuaypanich R. Nakhowong Program of Chemistry Faculty of Science Ubonratchathani Rajabhat University Ubon Ratchathani 34000 Thailand Functional Nanometerials and Electrospinning Research Laboratory Faculty of Science Ubonratchathani Rajabhat University Ubon Ratchathani 34000 Thailand Applied Chemistry Division Department of Chemistry and Center of Excellence for Innovations in Chemistry (PERCH-CIC) Faculty of Science Khon Kaen University Khon Kaen 40002 Thailand Materials Chemistry Research Center (MCRC-KKU) Faculty of Science Khon Kaen University Khon Kaen 40002 Thailand Program of Physics Faculty of Science Ubonratchathani Rajabhat University Ubon Ratchathani 34000 Thailand

Methylene blue (MB) was adsorbed on the mesoporous silica nanoparticles (MSN) and amine-functionalized mesoporous silica nanoparticles (MSN-NH 2 ). The adsorbent was synthesized biphasic method by co-condensation. A batch adsorption study was carried out of the MB with variable pH, adsorbent dosage and contact time. The MB dye could be removed by 0.05 g of adsorbent and 30 min contact time in the basic solution. The experimental data yielded excellent fits with Langmuir isotherm equations. The maximum adsorption capacity of MSN and MSN-NH 2 was calculated by Langmuir isotherm equations of 2.899 and 1.736 mg g -1 , respectively.

关键词： Mesoporous silica Nanospheres Biphasic Adsorption Amine-functionalization Methylene blue

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Visualization of dark excitons in semiconductor monolayers for high-sensitivity strain sensing

arXiv

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arXiv 2022年

作者： Chand, Saroj B. Woods, John M. Mejia, Enrique Taniguchi, Takashi Watanabe, Kenji Grosso, Gabriele Photonics Initiative Advanced Science Research Center City University of New York New YorkNY10031 United States International Center for Materials Nanoarchitectonics National Institute for Materials Science 1-1 Namiki Tsukuba305-0044 Japan Research Center for Functional Materials National Institute for Materials Science 1-1 Namiki Tsukuba305-0044 Japan Physics Program Graduate Center City University of New York New YorkNY10016 United States

Transition metal dichalcogenides (TMDs) are layered materials that have a semiconducting phase with many advantageous optoelectronic properties, including tightly bound excitons and spin-valley locking. In Tungsten-based TMDs, spin and momentum forbidden transitions give rise to dark excitons that typically are optically inaccessible but represent the lowest excitonic states of the system. Dark excitons can deeply affect transport, dynamics and coherence of bright excitons, hampering device performance. Therefore, it is crucial to create conditions in which these excitonic states can be visualized and controlled. Here, we show that compressive strain in WS2 enables phonon scattering of photoexcited electrons between momentum valleys, enhancing the formation of dark intervalley excitons. We show that the emission and spectral properties of momentum-forbidden excitons are accessible and strongly depend on the local strain environment that modifies the band alignment. This mechanism is further exploited for strain sensing in two-dimensional semiconductors revealing a gauge factor exceeding 104 Copyright © 2022, The Authors. All rights reserved.

关键词： Monolayers

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Electronic and Magnetic Properties of Topological Semimetal Candidate NdSbTe

arXiv

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arXiv 2020年

作者： Pandey, Krishna Basnet, Rabindra Wegner, Aaron Acharya, Gokul Un Nabi, Md Rafique Liu, Jiangwei Wang, Jian Takahashi, Yukiko Da, Bo Hu, Jin Materials Science and Engineering Program Institute for Nanoscience and Engineering University of Arkansas FayettevilleAR72701 United States Department of Physics University of Arkansas FayettevilleAR72701 United States Research Center for Functional Materials National Institute for Materials Science TsukubaIbaraki305-0047 Japan Institute for Materials Research Center for Spintronics Research Network Tohoku University Sendai980-8577 Japan Research Center for Magnetic and Spintronic Materials National Institute for Materials Science Sengen 1-2-1 TsukubaIbaraki305-0047 Japan Research and Services Division of Materials Data and Integrated System National Institute for Materials Science TsukubaIbaraki305-0044 Japan

ZrSiS-type materials represent a large material family with unusual coexistence of topological nonsymmorphic Dirac fermions and nodal-line fermions. As a special group of ZrSiS-family, LnSbTe (Ln = Lanthanide rare earth) compounds provide a unique opportunity to explore new quantum phases due to the intrinsic magnetism induced by Ln. Here we report the single crystal growth and characterization of NdSbTe, a previously unexplored LnSbTe compound. NdSbTe has an antiferromagnetic ground state with field-driven metamagnetic transitions similar to other known LnSbTe, but exhibits distinct enhanced electronic correlations characterized by large a Sommerfeld coefficient of 115 mJ/mol K2, which is the highest among the known LnSbTe compounds. Furthermore, our transport studies have revealed the coupling with magnetism and signatures of Kondo localization. All these findings establish NdSbTe as a new platform for observing novel phenomena arising from the interplay between magnetism, topology, and electron correlations. Copyright © 2020, The Authors. All rights reserved.

关键词： Topology

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Phase-engineered heterostructures of Mo2C by plasma-assisted selenization and sulfurization processes toward excellent hydrogen evolution reaction

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Nano Energy 2024年 122卷

作者： Kimbulapitiya, K.M.M.D.K. Rehman, Bushra Wani, Sumayah Shakil Chen, Chieh-Ting Cyu, Ruei-Hong Manikandan, Arumugam Date, Manisha Kondiba Peng, Yu-Ren Kumara, R.J.G.L.R. Chuang, Feng-Chuan Chueh, Yu-Lun Department of Physics National Sun Yat-sen University Kaohsiung80424 Taiwan Department of Materials Science and Engineering National Tsing-Hua University Hsinchu Taiwan College of Semiconductor Research National Tsing-Hua University Hsinchu30013 Taiwan Center for Nanotechnology Materials Science and Microsystem National Tsing-Hua University Hsinchu Taiwan Ph.D. Program in Prospective Functional Materials Industry National Tsing Hua University Hsinchu30013 Taiwan Physics Division National Center for Theoretical Sciences Hsinchu30013 Taiwan Center for Theoretical and Computational Physics National Sun Yat-Sen University Kaohsiung80424 Taiwan Department of Physics National Tsing Hua University Hsinchu30013 Taiwan

Due to the outstanding semiconducting and metallic properties, 2D materials such as Transition Metal dichalcogenides (TMDs) and Transition Metal Carbides (TMCs) appear to be promising candidate for Nano-scale electronics devices. Among them, 2D - Mo2C (Molybdenum carbide) has attracted attention as a new member of the MXene group, owing to its potential applications for superconductors, electronics devices, and catalysts for Hydrogen evolution Reactions (HER). Structural modification toward the creation of novel heterostructures with phase engineering opens new pathways for different applications. Herein, we prepared a large area Mo2C film by chemical vapor deposition method. The upper region of Mo2C layers can be oxidized to create Mo2C/MoOx heterostructures. Furthermore, those oxide layers were further transformed into MoSe2 and MoS2 by plasma-assisted selenization and sulfurization processes at different temperatures with a fixed plasma power of 150 W. The heterostructures demonstrated outstanding electrocatalytic activity for HER due to an existed metallic phase and active sites present after plasma-assisted selenization and sulfurization processes at the low temperature. The performance of the HER decreases at high temperatures owing to their semiconducting phase. The pristine Mo2C showed a Tafel slope of 72 mV dec−1 and an overpotential of 276 mV at 10 mA/cm2, while the Mo2C/MoSe2 heterostructure synthesized at 350 °C350 °exhibited an improved Tafel slope of 66 mV dec−1 and overpotential of 257 mV at 10 mA/ cm2. Additionally, the Mo2C/MoS2 heterostructure prepared at 350 °C also demonstrated a 263 mV improvement in overpotential at 10 mA/cm2. All the heterostructures showed excellent stability over a period of 10 h except Mo2C/MoOx. This work opens new strategies to fabricate high-quality MXene and TMDs heterostructures with metal-semiconductor interface. © 2024

关键词： Molybdenum compounds

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Optical generation, templating, and polymerization of three-dimensional arrays of liquid-crystal defects decorated by plasmonic nanoparticles

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Physical Review E 2013年第3期87卷 032503-032503页

作者： Julian S. Evans Paul J. Ackerman Dirk J. Broer Jao van de Lagemaat Ivan I. Smalyukh Department of Physics and Materials Science and Engineering Program University of Colorado at Boulder Boulder Colorado 80309 USA Department of Electrical Computer and Energy Engineering and Liquid Crystals Materials Research Center University of Colorado at Boulder Boulder Colorado 80309 USA National Renewable Energy Laboratory Golden Colorado 80401 USA Functional Organic Materials and Devices Eindhoven University of Technology Box 513 5600 MB Eindhoven The Netherlands Renewable and Sustainable Energy Institute National Renewable Energy Laboratory and University of Colorado at Boulder Boulder Colorado 80309 USA

Defects in liquid crystals are used to model topological entities ranging from Skyrmions in high-energy physics to early-universe cosmic strings, as well as find practical applications in self-assembly of diffraction gratings and in scaffolding of plasmonic nanoparticles, but they are hard to control and organize into three-dimensional lattices. We laterally scan focused laser beams to produce periodic arrays of twist-stabilized defects forming either linear (fingers) or axially symmetric (torons) configurations in partially polymerizable liquid crystal films. Polymerization allows for stabilization of these structures and the formation of three-dimensional arrays of defects by stacking of the thin cholesteric films on top of each other. In the process of fabrication of such arrays, we polymerize the liquid crystal film with an array of torons or fingers and then sequentially produce and photopolymerize new liquid crystal layers on top of it, thus obtaining a three-dimensional structure of twist-stabilized defects in a layer-by-layer fashion. Templating by the polymerized layer spontaneously yields ordered organization of fingers and torons in the new cholesteric layer, thus enabling a three-dimensional ordered structure of defects. Nondestructive three-dimensional imaging of director fields by use of three-photon excitation fluorescence polarizing microscopy reveals the nature of topological singularities and physical underpinnings behind the observed templating effect. Three-dimensional patterning of defects templates the self-assembly of plasmonic nanoparticles into individual singularities and their arrays, laying the groundwork for potential applications in nanophotonics, plasmonics, metamaterial fabrication, and nanoscale energy conversion.

关键词： LIQUID crystals CRYSTAL defects POLYMERIZATION DIMENSIONAL analysis PLASMONS (physics) NANOPARTICLES

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Emergence of new optical resonances in single-layer transition metal dichalcogenides with atomic-size phase patterns

arXiv

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arXiv 2022年

作者： Woods, John M. Chand, Saroj B. Mejia, Enrique Taniguchi, Takashi Watanabe, Kenji Flick, Johannes Grosso, Gabriele Photonics Initiative Advanced Science Research Center City University of New York New YorkNY United States International Center for Materials Nanoarchitectonics National Institute for Materials Science 1-1 Namiki Tsukuba305-0044 Japan Research Center for Functional Materials National Institute for Materials Science 1-1 Namiki Tsukuba305-0044 Japan Center for Computational Quantum Physics Flatiron Institute New YorkNY10010 United States Department of Physics City College of New York New YorkNY10031 United States Physics Program Graduate Center City University of New York New YorkNY10016 United States

Atomic-scale control of light-matter interactions represent the ultimate frontier for many applications in photonics and quantum technology. Two-dimensional semiconductors, including transition metal dichalcogenides, are a promising platform to achieve such control due to the combination of an atomically thin geometry and convenient photophysical properties. Here, we demonstrate that a variety of durable polymorphic structures can be combined to generate additional optical resonances beyond the standard excitons. We theoretically predict and experimentally show that atomic-sized patches of 1T phase within the 1H matrix form unique electronic bands that give rise to new and robust optical resonances with strong absorption, circularly polarized emission and long radiative lifetime. The atomic manipulation of two-dimensional semiconductors opens unexplored scenarios for light harvesting devices and exciton-based photonics. Copyright © 2022, The Authors. All rights reserved.

关键词： Excitons

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Electronic ratchet effect in a moiré system: signatures of excitonic ferroelectricity

arXiv

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arXiv 2023年

作者： Zheng, Zhiren Wang, Xueqiao Zhu, Ziyan Carr, Stephen Devakul, Trithep de la Barrera, Sergio Paul, Nisarga Huang, Zumeng Gao, Anyuan Zhang, Yang Bérubé, Damien Evancho, Kathryn Natasha Watanabe, Kenji Taniguchi, Takashi Fu, Liang Wang, Yao Xu, Su-Yang Kaxiras, Efthimios Jarillo-Herrero, Pablo Ma, Qiong Department of Physics Massachusetts Institute of Technology CambridgeMA United States Stanford Institute of Materials and Energy Science SLAC National Accelerator Laboratory Menlo ParkCA94025 United States Brown Theoretical Physics Center Department of Physics Brown University ProvidenceRI United States Department of Physics Boston College Chestnut HillMA United States Department of Chemistry and Chemical Biology Harvard University CambridgeMA United States Department of Physics and Astronomy Clemson University ClemsonSC United States Research Center for Functional Materials National Institute for Materials Science Tsukuba Japan International Center for Material Nanoarchitectonics National Institute for Materials Science Tsukuba Japan Department of Physics Harvard University CambridgeMA United States CIFAR Azrieli Global Scholars program CIFAR Toronto Canada

Electronic ferroelectricity represents a new paradigm where spontaneous symmetry breaking driven by electronic correlations, in contrast to traditional lattice-driven ferroelectricity, leads to the formation of electric dipoles. Despite the potential application advantages arising from its electronic nature, switchable electronic ferroelectricity remains exceedingly rare. Here, we report the discovery of an electronic ratchet effect that manifests itself as switchable electronic ferroelectricity in a layer-contrasting graphene-boron nitride moiré heterostructure. Our engineered layer-asymmetric moiré potential landscapes result in layer-polarized localized and itinerant electronic subsystems. At particular fillings of the localized subsystem, we find a ratcheting injection of itinerant carriers in a non-volatile manner, leading to a highly unusual ferroelectric response. Strikingly, the remnant polarization can be stabilized at multiple (quasi-continuous) states with behavior markedly distinct from known ferroelectrics. Our experimental observations, simulations, and theoretical analysis suggest that dipolar excitons are the driving force and elementary ferroelectric units in our system. This signifies a new type of electronic ferroelectricity where the formation of dipolar excitons with aligned moments generates a macroscopic polarization and leads to an electronically-driven ferroelectric response, which we term excitonic ferroelectricity. Such new ferroelectrics, driven by quantum objects like dipolar excitons, could pave the way to innovative quantum analog memory and synaptic devices. Copyright © 2023, The Authors. All rights reserved.

关键词： Ferroelectricity

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Preparation and properties of bimetallic Co/Cu ZIF-67 for electrochemical application 1

Preparation and properties of bimetallic Co/Cu ZIF-67 for el...

引用

1st Annual International Conference on Sensor Technology, INCOST 2023

作者： Wulandari, C. Gumilar, G. Nugraha Wasisto, H.S. Iqbal, M. Irzaman Nugroho, W.S. Rusydi, F. Doctoral Program of Engineering Physics Faculty of Industrial Technology Institut Teknologi Bandung Ganesha 10 Bandung40132 Indonesia Advanced Functional Materials Research Group Institut Teknologi Bandung Bandung40132 Indonesia PT Biostark Analitika Inovasi Bandung40375 Indonesia Bandung40135 Indonesia Research Center for Nanosciences and Nanotechnology Institut Teknologi Bandung Bandung40132 Indonesia PT Nanosense Instrument Indonesia Umbulharjo Yogyakarta55167 Indonesia Department of Physics Faculty of Mathematics and Natural Sciences IPB University Bogor16680 Indonesia Departement of Veterinary Public Health Faculty of Veterinary Medicine Universitas Gadjah Mada Yogyakarta55281 Indonesia Department of Physics Faculty of Science and Technology Universitas Airlangga Surabaya60115 Indonesia

Efforts to enhance the electrochemical properties of materials have become the focus of numerous studies because these properties are essential in various fields of application. Zeolitic imidazole framework-67 (ZIF-67) is a type of metal-organic framework (MOFs) expected to demonstrate excellent performance in electrochemical applications due to its numerous distinct properties. Consequently, various strategies and techniques have been developed to improve the electrochemical performance of ZIF-67. In this study, we employed bimetallic ZIF-67 constructed with cobalt (Co) and copper (Cu) metal ions within the imidazole frameworks. The use of bimetal is expected to increase conductivity and fine-tune the physicochemical properties of ZIF-67. Using coprecipitation methods, we synthesized both single-metal and bimetallic ZIF-67 and compared their characterizations. The addition of Cu metal ions does not alter the materials phase, ensuring compatibility with the single-metal ZIF-67 structure. However, the rhombic dodecahedron morphology of ZIF-67 shifts from a smooth to a concave and rough surface in Co/Cu ZIF-67. Furthermore, Co/Cu ZIF-67 exhibits higher peak current on their cyclic voltammetry (CV) curve by 46.15 μA. The results effectively illustrate the advantages of bimetal on ZIF-67 properties and performance. Finally, this study succesfully briefly demonstrate the potential development of Co/Cu-based ZIF-67 for various electrochemical applications. © Published under licence by IOP Publishing Ltd.

关键词： Metal ions

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