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arXiv 2023年

作者： Wu, Han Zhu, Jian-Xin Chen, Lebing Butcher, Matthew W. Yue, Ziqin Yuan, Dongsheng He, Yu Oh, Ji Seop Huang, Jianwei Wu, Shan Gong, Cheng Guo, Yucheng Mo, Sung-Kwan Denlinger, Jonathan D. Lu, Donghui Hashimoto, Makoto Stone, Matthew B. Kolesnikov, Alexander I. Chi, Songxue Kono, Junichiro Nevidomskyy, Andriy H. Birgeneau, Robert J. Dai, Pengcheng Yi, Ming Department of Physics and Astronomy Rice Center for Quantum Materials Rice University HoustonTX77005 United States Theoretical Division Los Alamos National Laboratory Los AlamosNM87545 United States Center for Integrated Nanotechnologies Los Alamos National Laboratory Los AlamosNM87545 United States Department of Physics University of California at Berkeley BerkeleyCA94720 United States Applied Physics Graduate Program Smalley-Curl Institute Rice University HoustonTX77005 United States Materials Sciences Division Lawrence Berkeley National Laboratory BerkeleyCA94720 United States 1-1 Namiki Ibaraki Tsukuba305-0044 Japan Department of Applied Physics Yale University New HavenCT06511 United States Department of Electrical and Computer Engineering Quantum Technology Center University of Maryland College ParkMD20742 United States Advanced Light Source Lawrence Berkeley National Laboratory BerkeleyCA94720 United States Stanford Synchrotron Radiation Lightsource SLAC National Accelerator Laboratory Menlo ParkCA94025 United States Neutron Scattering Division Oak Ridge National Laboratory Oak RidgeTN37831 United States Department of Electrical and Computer Engineering Rice University HoustonTX77005 United States Smalley-Curl Institute Rice University HoustonTX77005 United States Department of Material Science and NanoEngineering Rice University HoustonTX77005 United States Department of Materials Science and Engineering University of California Berkeley United States

The two-dimensional (2D) material Cr2Ge2Te6 is a member of the class of insulating van der Waals magnets. Here, using high resolution angle-resolved photoemission spectroscopy in a detailed temperature dependence study, we identify a clear response of the electronic structure to a dimensional crossover in the form of two distinct temperature scales marking onsets of modifications in the electronic structure. Specifically, we observe Te p-orbital-dominated bands to undergo changes at the Curie transition temperature TC while the Cr d-orbital-dominated bands begin evolving at a higher temperature scale. Combined with neutron scattering, density functional theory calculations, and Monte Carlo simulations, we find that the electronic system can be consistently understood to respond sequentially to the distinct temperatures at which in-plane and out-of-plane spin correlations exceed a characteristic length scale. Our findings reveal the sensitivity of the orbital-selective electronic structure for probing the dynamical evolution of local moment correlations in vdW insulating magnets. © 2023, CC BY.

关键词： Electronic structure

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Transparent, low-autofluorescence microECoG device for simultaneous Ca2+ imaging and cortical electrophysiology in vivo

Transparent, low-autofluorescence microECoG device for simul...

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作者： Zátonyi, A. Madarász, M. Szabó, O. Lőrincz, T. Hodován, R. Rózsa, B. Fekete, Z. Research Group for Implantable Microsystems Faculty of Information Technology and Bionics Pázmány Péter Catholic University Budapest Hungary Microsystems Laboratory Institute for Technical Physics and Material Sciences Centre for Energy Research HAS Budapest Hungary Doctoral School of Chemical Engineering and Material Sciences University of Pannonia Veszprém Hungary Laboratory of 3D Functional Network and Dendritic Imaging Institute of Experimental Medicine HAS Budapest Hungary János Szentágothai PhD Program Semmelweis University Budapest Hungary Roska Tamás Doctoral School of Sciences and Technology Pázmány Péter Catholic University Budapest Hungary

Objective. Multimodal neuroimaging approaches are beneficial to discover brain functionalities at high spatial and temporal resolution. In our work, a novel material composition of a microECoG device relying on Parylene HT and indium-tin-oxide (ITO) is presented, which facilitates two-photon imaging of Ca2+ signals and concurrent recording of cortical EEG. Approach. Long-term stability of the interfaces of the transparent microdevice is confirmed in vitro by electrochemical and mechanical tests. The outstanding optical properties, like high transmittance and low auto-fluorescent are proven by fluorimetric measurements. Spatial resolution of fluorescent two-photon imaging through the microECoG device is presented in transgenic hippocampal slices, while concurrent recording of Ca2+ signals and cortical EEG is demonstrated in vivo. Photoartefacts and photodegradation of the materials are also investigated in detail to provide safety guidelines for further use in two-photon in vivo imaging schemes. Main results. Two-photon imaging of Ca signals can be safely performed through the proposed transparent ECoG device, without significant distortion in the dimensions of detected neuronal structures or in the temporal signaling. In chronic use, we demonstrated that fluorescent Ca signals of individual neurons can be clearly recorded even after 51 d. Significance. Our results give a firm indication that highly transparent microECoG electrode arrays made of Parylene HT/ITO/Parylene HT multilayer are excellent candidates for synergetic recording of optical signals and EEG from intact brains with high resolution and are free of electrical and optical artefacts. © 2020 IOP Publishing Ltd.

关键词： Electrophysiology

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Coconut waste to green nanomaterial: Large scale synthesis of N-doped graphene nano sheets

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Nano-Structures and Nano-Objects 2023年 36卷

作者： Siburian, Rikson Tang, Liang Wei Alias, Yatimah Tok, Alfred Iing Yoong Goei, Ronn Simanjuntak, Crystina Tarigan, Kerista Paiman, Suriati Goh, Boon Tong Anshori, Isa Kurniawan, Cepi Postgraduate Program Department of Chemistry Faculty of Mathematics and Natural Sciences Universitas Sumatera Utara Medan 20155 Indonesia Department of Chemistry Faculty of Mathematics and Natural Sciences Universitas Sumatera Utara Medan 20155 Indonesia Carbon and Frankincense Research Center Universitas Sumatera Utara Medan 20155 Indonesia Department of Chemistry Faculty of Science Universiti Malaya Kuala Lumpur 50603 Malaysia University Malaya Centre for Ionic Liquids (UMCiL) Universiti Malaya Kuala Lumpur 50603 Malaysia School of Materials Science and Engineering Nanyang Technological University 50 Nanyang Avenue Singapore 639798 Singapore Department of Physics Faculty of Mathematics and Natural Sciences Universitas Sumatera Utara Medan 20155 Indonesia Physics Department Faculty of Science Universiti Putra Malaysia Selangor (Serdang) Seri Kembangan 43400 Malaysia Low Dimensional Materials Research Centre Department of Physics Faculty of Science University of Malaya Kuala Lumpur 50603 Malaysia Biomedical Engineering Department School of Electrical Engineering and Informatics Bandung Institute of Technology Bandung 40132 Indonesia Research Center of Nanoscience and Nanotechnology Bandung Institute of Technology Bandung 40132 Indonesia Chemistry Department Faculty of Mathematics and Natural Sciences Universitas Negeri Semarang Semarang 50229 Indonesia Functional Material Research Center Universitas Negeri Semarang Semarang 50229 Indonesia

In this paper, a breakthrough was achieved in large-scale production of N-doped Graphene Nano Sheets (N-GNS) using coconut fruits. The main objectives were to produce N-GNS on a large scale and assess its electrical conductivity. The process involved two key steps: first, producing GNS from coconut fruits through pyrolysis, and then generating N-GNS by doping with nitrogen using ammonia solution at room temperature. Various analytical techniques were used to characterize the produced N-GNS, including X-ray Diffraction (XRD), Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM-EDS), Transmission Electron Microscopy (TEM), X-ray Photoelectron Spectroscopy (XPS), Raman spectroscopy, and electrochemical cyclic voltammetry and electrochemical impedance spectroscopy. The XRD data indicated that the C (002) peak of N-GNS shifted to a higher 2θ value (2θ = 24.72°) compared to GNS (2θ = 23.86°), suggesting an incorporation of nitrogen into carbon structure in N-GNS. This was further supported by XPS data, which identified N-pyridine (BE = 402.0 eV) and C-N (BE = 286.8 eV) in N-GNS. TEM images showed that N-GNS had a flat surface, and the distance between graphene layers slightly expanded (0.36 nm) compared to graphene layers (0.34 nm). SEM images and EDX data validated the morphology, resembling honeycomb lattices, with a significant content of N atoms. Raman data successfully identified the D-band and G-band in N-GNS, further validating its production. Most importantly, N-GNS exhibited electrical conductivity, making it a promising candidate for conductive and supporting materials in various applications. The significance of this research extends beyond N-GNS production, opening up new avenues for the sustainable synthesis of valuable nanomaterials from coconut fruit waste, contributing to both graphene technology and environmental conservation. © 2023 Elsevier B.V.

关键词： C-sp2 Electrical conductivity Graphene nano sheets N-graphene nano sheets N-pyridine XPS

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Exploring the hydrogen storage potential of lead-free rubidium based perovskite hydrides: A first-principles study

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International Journal of Hydrogen Energy 2025年 147卷

作者： M. Kashif Masood Wahidullah Khan Shumaila Bibi Muniba Urooj Arooj Ali Javed Rehman Aboud Ahmed Awadh Bahajjaj Department of Physics and Hebei Advanced Thin Film Laboratory Hebei Normal University Shijiazhuang 050024 China Post Graduate Program of Material Science UFRGS RS 91501- 970 Brazil Institute of Chemistry The Islamia University of Bahawalpur 63100 Pakistan College of Materials Science and Engineering Jilin University Changchun 130012 China Institute of Physics The Islamia University of Bahawalpur 63100 Pakistan State Key Laboratory of Metastable Materials Science and Technology and School of Materials Science and Engineering Yanshan University Qinhuangdao 066004 China MEU Research Unit Middle East University Amman 11831 Jordan Department of Chemistry College of Science King Saud University Riyadh 11451 Saudi Arabia

The structural, mechanical, electrical, magnetic, thermodynamic, optical, and hydrogen storage characteristics of innovative RbXH 3 (X = Sc and Y) perovskite hydrides were thoroughly analyzed, employing a detailed density functional theory (DFT) investigation. By calculating formation energy, cohesive energy, and elastic moduli, it was determined that ScXH 3 materials showed remarkable thermal and mechanical stability. Structural properties indicated that RbYH 3 has high ionic radii, crystal structure, and lattice parameters as compared to RbScH 3 . To assess these materials' metallic nature, overall band structure and electronic density of state data are being analyzed. The B/G ratio (Pugh's ratio) analysis indicates that these materials exhibit tunable properties. The bulk of their bond types are ionic in nature, according to further study. It is concluded that these compounds are non-magnetic order conductors based on their magnetic properties. In addition, these materials have remarkable optical properties with high conductivity, dielectric function, absorption, and refractive index. Our findings indicate that RbScH 3 with precise and superior optical characteristics is a superior hydride. The vibrational stability of these crystalline compounds was thoroughly evaluated through molecular dynamics simulations and phonon dispersion curves. Furthermore, the capacity of hydrogen storage of RbXH 3 compounds was quantified, RbScH 3 achieving 2.27 wt % and RbYH 3 yielding 1.71 wt%. The calculated desorption temperatures and formation energies for RbScH 3 and RbYH 3 are 374 K and 426 K, and −0.51 eV/atom and −0.58 eV/atom, respectively. This study signifies the first comprehensive investigation of RbXH 3 perovskite hydrides, paving the way for innovative advancements in the field of hydrogen storage materials.

关键词： Density functional theory Desorption temperature H2 storage capacity Hydride-based perovskites RbXH3

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Publisher's Note: “Sub-100 nm high spatial frequency periodic structures driven by femtosecond laser induced desorption in GaAs” [Appl. Phys Lett. 118, 242106 (2021)]

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Applied physics Letters 2021年第1期119卷

作者： Alex Sarracino Abdul R. Ansari Ben Torralva Steven Yalisove 1Applied Physics Program University of Michigan Ann Arbor Michigan 48104 USA 2Material Science and Engineering University of Michigan Ann Arbor Michigan 48109 USA

This article was originally published online on 17 June 2021 with errors.

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Emergent magnetic ordering and topological frustration in quasicrystal artificial spin ices

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Physical Review B 2019年第9期99卷 094424-094424页

作者： F. Barrows V. Brajuskovic A. K. Petford-Long C. Phatak Material Science Division Argonne National Laboratory Argonne Illinois 60439 USA Applied Physics Program Northwestern University Evanston Illinois 60208 USA Department of Materials Science and Engineering Northwestern University Evanston Illinois 60208 USA

Artificial spin ices (ASIs) are nanoscale geometrically engineered arrays of magnetic bars or islands that display magnetic frustration and provide a fertile system for modeling and testing many complex statistical mechanics theories and emergent phenomena. Aperiodic ASIs display spatially varying magnetic frustration as a result of the aperiodicity. We have explored the magnetization reversal of quasicrystalline ASIs (QC-ASIs) patterned on P2 and P3 Penrose tilings, using a statistical graph-theory approach that enables quantitative comparison between the two tilings. Our approach offers insight into the QC-ASIs. We show that the P2 tiling leads to enhanced topological frustration compared to the P3 tiling, and we elucidate the emergence of local antiferromagnetic ordering as well as disordered states in these ferromagnetic aperiodic lattices. Our method enables quantitative exploration of frustration behavior on any periodic or aperiodic lattice, thereby opening pathways to study collective behavior in various topologically frustrated systems.

关键词： Magnetic interactions Magnetic order Magnetism

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Chemical evolution of some selected complex organic molecules in low-mass star-forming regions

arXiv

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arXiv 2023年

作者： Bhat, Bratati Kar, Rumela Mondal, Suman Kumar Ghosh, Rana Gorai, Prasanta Shimonishi, Takashi Tanaka, Kei E.I. Furuya, Kenji Das, Ankan Institute of Astronomy Space and Earth Science 1 Bidhan Sishu Sarani Kolkata700054 India Department of Metallurgical Engineering and Material Sciences IIT Bombay Powai Maharashtra Mumbai400076 India S. N. Bose National Center for Basic Sciences JD-Block Salt Lake Kolkata700098 India Indian Centre for Space Physics 43 Chalantika Garia Station Road Kolkata700084 India Department of Space Earth & Environment Chalmers University of Technology GothenburgSE-412 96 Sweden Center for Transdisciplinary Research Niigata University Niigata Nishi-ku950-2181 Japan Environmental Science Program Department of Science Faculty of Science Niigata University Niigata Nishi-ku950-2181 Japan Department of Earth and Planetary Sciences Tokyo Institute of Technology Meguro Tokyo152-8551 Japan Center for Computational Sciences University of Tsukuba Tsukuba305-8577 Japan National Astronomical Observatory of Japan Tokyo181-8588 Japan

The destiny of complex organic molecules (COMs) in star-forming regions is interlinked with various evolutionary phases. Therefore, identifying these species in diversified environments of identical star-forming regions would help to comprehend their physical and chemical heritage. We identified multiple COMs utilizing the Large program ‘Astrochemical Surveys At IRAM’ (ASAI) data, dedicated to chemical surveys in Sun-like star-forming regions with the IRAM 30 m telescope. It was an unbiased survey in the millimeter regime, covering the prestellar core, protostar, outflow region, and protoplanetary disk phase. Here, we have reported some transitions of seven COMs, namely, methanol (CH3OH), acetaldehyde (CH3CHO), methyl formate (CH3OCHO), ethanol (C2H5OH), propynal (HCCCHO), dimethyl ether (CH3OCH3), and methyl cyanide (CH3CN) in some sources L1544, B1-b, IRAS4A, and SVS13A. We found a trend among these species from the derived abundances using the rotational diagram method and MCMC fit. We have found that the abundances of all of the COMs, except for HCCCHO, increase from the L1544 (prestellar core) and peaks at IRAS16293-2422 (class 0 phase). It is noticed that the abundance of these molecules correlate with the luminosity of the sources. The obtained trend is also visible from the previous interferometric observations and considering the beam dilution effect. Copyright © 2023, The Authors. All rights reserved.

关键词： Molecules

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Microscopic picture of paraelectric perovskites from structural prototypes

arXiv

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arXiv 2021年

作者： Kotiuga, Michele Halilov, Samed Kozinsky, Boris Fornari, Marco Marzari, Nicola Pizzi, Giovanni École Polytechnique Fédérale de Lausanne LausanneCH-1015 Switzerland Designed Material Technologies LLC P.O. Box 14548 RichmondVA23221-9998 United States John A. Paulson School of Engineering and Applied Sciences Harvard University 29 Oxford Street CambridgeMA02138 United States Robert Bosch LLC Research and Technology Center CambridgeMA02139 United States Department of Physics Science of Advanced Materials Program Central Michigan University Mt. PleasantMI48859 United States

We highlight with first-principles molecular dynamics the persistence of intrinsic h111i Ti off-centerings for BaTiO3 in its cubic paraelectric phase. Intriguingly, these are inconsistent with the Pm¯3m space group often used to atomistically model this phase using density functional theory or similar methods. Therefore we deploy a systematic symmetry analysis to construct representative structural models in the form of supercells that satisfy a desired point symmetry but are built from the combination of lower-symmetry primitive cells. We define as structural prototypes the smallest of these that are both energetically and dynamically stable. Remarkably, two 40-atom prototypes can be identified for paraelectric BaTiO3;these are also common to many other ABO3 perovskites. These prototypes can offer structural models of paraelectric phases that can be used for the computational engineering of functional materials. Last, we show that the emergence of B-cation off-centerings and the primitive-cell phonon instabilities is controlled by the equilibrium volume, in turn dictated by the filler A cation. © 2021, CC BY.

关键词： Positive ions

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Mapping the Non-Monotonic Ageing of Metallic Glasses in the Metastability-Temperature Space

SSRN

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SSRN 2019年

作者： Liu, Chaoyi Yan, Xin Sharma, Pradeep Fan, Yue Department of Mechanical Engineering University of Michigan Ann Arbor United States School of Mechanical Engineering and Automation Beihang University Beijing China Department of Mechanical Engineering University of Houston Department of Physics University of Houston Material Science and Engineering Program University of Houston

Ageing behaviors of metallic glasses are investigated by atomistic modeling in a broad range of processing histories and thermal conditions. By employing an enhanced data-mining analysis, a non-monotonic ageing phenomenon is resolved with high precision. It is observed that there exists a non-linear correlation between the system's metastability and the critical temperature where maximum ageing rate occurs. In further conjunction with the recently developed energy landscape theory to circumvent the time-scale limitations of molecular dynamics, the ageing rate contours over ten orders of magnitude are mapped out in the metastability-temperature space. Such map enables a natural explanation to the experimentally observed shift of exothermic signal, which cannot be provided by existing models. Implications of the present study for understanding the mechanical properties of amorphous alloys are also discussed. © 2019, The Authors. All rights reserved.

关键词： Computation theory

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Robust Coupling between Structural and Electronic Transitions in a Mott material

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Physical Review Letters 2019年第5期122卷 057601-057601页

作者： Yoav Kalcheim Nikita Butakov Nicolas M. Vargas Min-Han Lee Javier del Valle Juan Trastoy Pavel Salev Jon Schuller Ivan K. Schuller Department of Physics and Center for Advanced Nanoscience University of California San Diego La Jolla California 92093 USA Department of Electrical and Computer Engineering University of California Santa Barbara Santa Barbara California 93106 USA Material Science and Engineering Program University of California San Diego La Jolla California 92093 USA

The interdependences of different phase transitions in Mott materials are fundamental to the understanding of the mechanisms behind them. One of the most important relations is between the ubiquitous structural and electronic transitions. Using IR spectroscopy, optical reflectivity, and x-ray diffraction, we show that the metal-insulator transition is coupled to the structural phase transition in V2O3 films. This coupling persists even in films with widely varying transition temperatures and strains. Our findings are in contrast to recent experimental findings and theoretical predictions. Using V2O3 as a model system, we discuss the pitfalls in measurements of the electronic and structural states of Mott materials in general, calling for a critical examination of previous work in this field. Our findings also have important implications for the performance of Mott materials in next-generation neuromorphic computing technology.

关键词： Crystal growth Crystal orientation Crystal structure Crystal symmetry Crystallization Electronic structure Peierls transition Phase transitions Spin state transition Strain Antiferromagnets Mott insulators Stimuli-responsive materials Strongly correlated systems Thin films Cavity resonators Crystallography Fourier transform infrared spectroscopy Resistivity measurements Scanning techniques Sputtering Strain engineering X-ray diffraction

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