检索结果-内蒙古大学图书馆

Nernst-Ettingshausen effect in thin Pt and W films at low temperatures

学校读者我要写书评

暂无评论

arXiv 2023年

作者： Luo, Renjie Legvold, Tanner J. Chen, Liyang Natelson, Douglas Department of Physics and Astronomy Rice University HoustonTX77005 United States Applied Physics Graduate Program Smalley-Curl Institute Rice University HoustonTX77005 United States Department of Electrical and Computer Engineering Department of Materials Science and NanoEngineering Rice University HoustonTX77005 United States

As spin caloritronic measurements become increasingly common techniques for characterizing material properties, it is important to quantify potentially confounding effects. We report measurements of the Nernst-Ettingshausen response from room temperature to 5 K in thin film wires of Pt and W, metals commonly used as inverse spin Hall detectors in spin Seebeck characterization. Johnson-Nyquist noise thermometry is used to assess the temperature change of the metals with heater power at low temperatures, and the thermal path is analyzed via finite-element modeling. The Nernst-Ettingshausen response of W is found to be approximately temperature-independent, while the response of Pt increases at low temperatures. These results are discussed in the context of theoretical expectations and the possible role of magnetic impurities in Pt. Copyright © 2023, The Authors. All rights reserved.

关键词： Inverse problems

Unusual thermal properties of graphene origami crease:A molecular dynamics study

学校读者我要写书评

暂无评论

Green Energy & Environment 2022年第1期7卷 86-94页

作者： Ning Wei Yang Chen Kun Cai Yingyan Zhang Qingxiang Pei Jin-Cheng Zheng Yiu-Wing Mai Junhua Zhao Jiangsu Key Laboratory of Advanced Food Manufacturing Equipment and Technology Jiangnan UniversityWuxi214122China Shanghai Institute of Applied Mathematics and Mechanics Shanghai Key Laboratory of Mechanics in Energy EngineeringShanghai UniversityShanghai200072China School of Engineering RMIT UniversityBundooraVIC3083Australia Institute of High Performance Computing A^(*)STAR138632Singapore Department of Physics and the Collaborative Innovation Center for Optoelectronic Semiconductors and Efficient Devices Xiamen UniversityXiamen361005China Xiamen University Malaysia 439000SepangSelangorMalaysia Centre for Advanced Materials Technology(CAMT) School of AerospaceMechanical and Mechatronic Engineering J07The University of SydneySydneyNSW2006Australia

Graphene is a two-dimensional material that can be folded into diverse and yet interesting nanostructures like macro-scale paper *** of graphene not only makes different morphological configurations but also modifies their mechanical and thermal *** by paper origami,herein we studied systemically the effects of creases,where sp^(2)to sp^(3)bond transformation occurs,on the thermal properties of graphene origami using molecular dynamics(MD)*** MD simulation results show that tensile strain reduces(not increases)the interfacial thermal resistance owing to the presence of the *** unusual phenomenon is explained by the micro-heat flux migration and stress *** findings on the graphene origami enable the design of the next-generation thermal management devices and flexible electronics with tuneable properties.

关键词： Graphene Origami Bond transformation Interfacial thermal resistance Molecular dynamics

Experimental Study and Atomistic Simulations on Gadolinium-Doped Manganese-Barium Based Y-Type Hexaferrites for Magnetic Hyperthermia

学校读者我要写书评

暂无评论

SSRN

SSRN 2023年

作者： Khan Asghar, H.M. Noor ul Huda Ali, Muzaffar Gilani, Zaheer Abbas Shar, Muhammad Ali Ali, Syed Mansoor Khan, Muhammad Azhar Hisham, M. Manzoor, Alina Haq, Siraj Ul Rashid, Amin Ur Khan, Muhammad Yaqoob Department of Physics Balochistan University of Information Technology Engineering & Management Sciences Quetta87300 Pakistan Department of Mechanical & Energy Systems Engineering Faculty of Engineering and Informatics University of Bradford BradfordBD7 1DP United Kingdom Department of Physics and Astronomy College of Science King Saud University P.O. Box 2455 Riyadh11451 Saudi Arabia Institute of Physics The Islamia University of Bahawalpur Bahawalpur63100 Pakistan Department of Applied Physics Federal Urdu University of Arts Science and Technology Islamabad Pakistan Department of Physics Government College University Faisalabad38000 Pakistan Department of Physics Pukyong National University Busan48513 Korea Republic of Department of Applied Physical & Material Sciences University of Swat Pakistan Department of Physics Kohat University of Science and Technology Khyber Pakhtunkhwa Kohat26000 Pakistan

Gd-doped manganese barium y-type hexaferrite nanoparticles (Mn2Ba2GdxFe12-xO22) were synthesized using the sol-gel method. The magnetic properties, including saturation magnetization, coercivity, and Curie temperature (TC), were investigated for varying Gd concentrations (x = 0.00, 0.05, 0.10, 0.15, 0.20, 0.25). Results showed a decrease in these properties with increasing Gd concentration. The TC ranged from 254 K to 290 K. The experimental findings were compared to simulations conducted using the Vampire atomistic simulator, showing good agreement with the experimental TC values. Additionally, the samples were subjected to an alternating magnetic field with amplitude 170 Ôe and frequencies of 327 kHz and 734 kHz. Specific absorption rate (SAR) values were measured which increased with higher Gd concentration, peaking at 341 W/g for an alternating magnetic field of 170 Ôe and frequency of 734 kHz. Despite the TC being below the therapeutic range of 315 – 320 K, the samples exhibited high SAR values. © 2023, The Authors. All rights reserved.

关键词： Barium

Ab Initio Structure Solutions from Nanocrystalline Powder Diffraction Data via Diffusion Models

学校读者我要写书评

暂无评论

arXiv 2024年

作者： Guo, Gabe Saidi, Tristan Luca Terban, Maxwell W. Valsecchi, Michele Billinge, Simon J.L. Lipson, Hod Columbia University Department of Computer Science New YorkNY10027 United States Momentum Transfer Mannheim68169 Germany Columbia University Department of Chemical Engineering New YorkNY10027 United States Columbia University Department of Applied Physics and Applied Mathematics New YorkNY10027 United States Columbia University Department of Mechanical Engineering New YorkNY10027 United States Stanford University Department of Computer Science StanfordCA94305 United States

A major challenge in materials science is the determination of the structure of nanometer sized objects. Here we present a novel approach that uses a generative machine learning model based on diffusion processes that is trained on 45,229 known structures. The model factors both the measured diffraction pattern as well as relevant statistical priors on the unit cell of atomic cluster structures. Conditioned only on the chemical formula and the information-scarce finite-size broadened powder diffraction pattern, we find that our model, PXRDNET, can successfully solve simulated nanocrystals as small as 10 Å across 200 materials of varying symmetry and complexity, including structures from all seven crystal systems. We show that our model can successfully and verifiably determine structural candidates four out of five times, with average error among these candidates being only 7% (as measured by post-Rietveld refinement R-factor). Furthermore, PXRDNET is capable of solving structures from noisy diffraction patterns gathered in real-world experiments. We suggest that data driven approaches, bootstrapped from theoretical simulation, will ultimately provide a path towards determining the structure of previously unsolved nano-materials. Copyright © 2024, The Authors. All rights reserved.

关键词： Rietveld refinement

Nanoscale ferroelectric domain switching and thickness scaling impact in undoped hafnium-oxide ferroelectric devices

学校读者我要写书评

暂无评论

Thin Solid Films 2024年 799卷

作者： Fan, Chia-Chi Chen, Hsuan-Han Liao, Ruo-Yin Chou, Wu-Ching Huang, Ching-Chien Hsu, Hsiao-Hsuan Han, Su-Ting Cheng, Chun-Hu Department of Electronics Engineering National Yang Ming Chiao Tung University Hsinchu30010 Taiwan Department of Electro-Physics National Yang Ming Chiao Tung University Hsinchu30010 Taiwan Department of Mechanical Engineering National Kaohsiung University of Science and Technology Kaohsiung80778 Taiwan Institute of Materials Science and Engineering National Taipei University of Technology Taipei10608 Taiwan Department of Applied Biology and Chemical Technology The Hong Kong Polytechnic University Hunghom Hong Kong Department of Mechatronic Engineering National Taiwan Normal University Taipei10610 Taiwan

In this work, we investigated the polarization characteristics of nanoscale undoped hafnium oxide (HfO2) ferroelectric film. The nanoscale domain switching behavior of undoped HfO2 is mainly dominated by mixed ferroelectric/nonferroelectric crystalline phases and interface domain pinning by oxygen vacancies or defect traps. Our experimental results confirm that these issues can be improved by film thickness scaling and well-controlled mechanical stress. We demonstrated a 4-nm-thick undoped HfO2 negative capacitance thin film transistor (NCFET) with an energy-efficient switch characteristic of a low overdrive voltage of -0.6 V, a steep subthreshold swing of sub-60 mV/dec and a uniform hysteresis distribution of sub-60 mV. © 2024 Elsevier B.V.

关键词： Hafnium oxides

Visual anemometry of natural vegetation from their leaf motion

学校读者我要写书评

暂无评论

arXiv 2025年

作者： Goldshmid, Roni H. Dabiri, John O. Sader, John E. Graduate Aerospace Laboratories California Institute of Technology PasadenaCA91125 United States Department of Aerospace Engineering San Diego State University San DiegoCA92182 United States Department of Mechanical and Civil Engineering California Institute of Technology PasadenaCA91125 United States Department of Applied Physics and Materials Science California Institute of Technology PasadenaCA91125 United States

High-resolution, near-ground wind-speed data are critical for improving the accuracy of weather predictions and climate models,1–3 supporting wildBire control efforts,4–7 and ensuring the safe passage of airplanes during takeoff and landing maneouvers.8,9 Quantitative wind speed anemometry generally employs on-site instrumentation for accurate single-position data or sophisticated remote techniques such as Doppler radar for quantitative Bield measurements. It is widely recognized that the wind-induced motion of vegetation depends in a complex manner on their structure and mechanical properties, obviating their use in quantitative anemometry.10–14 We analyze measurements on a host of different vegetation showing that leaf motion can be decoupled from the leaf’s branch and support structure, at low-to-moderate wind speed, U!"#$. This wind speed range is characterized by a leaf Reynolds number, enabling the development of a remote, quantitative anemometry method based on the formula, U!"#$ ≈ 740&μU%&'(/pD, that relies only on the leaf size D, its measured Bluctuating (RMS) speed U%&'(, the air viscosity μ, and its mass density p. This formula is corroborated by a Birst-principles model and validated using a host of laboratory and Bield tests on diverse vegetation types, ranging from oak, olive, and magnolia trees through to camphor and bullgrass. The Bindings of this study open the door to a new paradigm in anemometry, using natural vegetation to enable remote and rapid quantitative Bield measurements at global locations with minimal cost. Copyright © 2025, The Authors. All rights reserved.

关键词： Weather forecasting

Retraction Note: Enhanced optical and thermal conductivity properties of barium titanate ceramic via strontium doping for thermo-optical applications

学校读者我要写书评

暂无评论

Optical and Quantum Electronics 2024年第1期57卷 1-2页

作者： Tihtih, Mohammed Eldin F. M. Ibrahim, Jamal A. Basyooni, Mohamed En‑nadir, Redouane Belaid, Walid M. Abdelfattah, Mohamed Hussainova, Irina Pszota, Gábor Kocserha, István Institute of Ceramics and Polymer Engineering University of Miskolc Miskolc Hungary Department of Nanotechnology and Advanced Materials Graduate School of Applied and Natural Science Selçuk University Konya Turkey Science and Technology Research and Application Center (BITAM) Necmettin Erbakan University Konya Turkey LPS Faculty of Sciences Sidi Mohamed Ben Abdellah University Fez Morocco Department of Physics Faculty of Science Selçuk University Konya Turkey Department of Mechanical and Industrial Engineering Tallinn University of Technology Tallinn Estonia Institute of Physics and Electrical Engineering University of Miskolc Miskolc Hungary

Characterizing the mechanical response of metallic glasses to uniaxial tension using a spring network model

学校读者我要写书评

暂无评论

arXiv 2023年

作者： Nawano, Aya Schroers, Jan Shattuck, Mark D. O’Hern, Corey S. Department of Mechanical Engineering and Materials Science Yale University New HavenCT06520 United States Benjamin Levich Institute and Physics Department The City College of New York New YorkNY10031 United States Department of Physics Yale University New HavenCT06520 United States Department of Applied Physics Yale University New HavenCT06520 United States Graduate Program in Computational Biology and Bioinformatics Yale University New HavenCT06520 United States

Metallic glasses are frequently used as structural materials. Therefore, it is important to develop methods to predict their mechanical response as a function of the microstructure prior to loading. We develop a novel coarse-grained spring network model, which describes the mechanical response of metallic glasses using an equivalent series network of springs, which can break and re-form to mimic atomic rearrangements during deformation. To validate the spring network model, we perform numerical simulations of quasistatic, uniaxial tensile deformation of Lennard-Jones and embedded atom method (EAM) potentials for Cu50Zr50 metallic glasses in the absence of large-scale shear band formation. We consider samples prepared using a wide range of cooling rates and with different amounts of crystalline order. We show that both the Lennard-Jones and EAM models possess qualitatively similar stress σ versus strain γ curves. By specifying five parameters in the spring network model (ultimate strength, strain at ultimate strength, slopes of σ(γ) at γ = 0 and at large strain, and strain at fracture where σ = 0), we can accurately describe the form of the stress-strain curves during uniaxial tension for the computational studies of Cu50Zr50, as well as recent experimental studies of several Zr-based metallic glasses. For the computational studies of Cu50Zr50, we find that the yield strain distribution is shifted to larger strains for slowly cooled glasses compared to rapidly cooled glasses. In addition, the average number of new springs and their rate of formation decreases with decreasing cooling rate. These effects offset each other at large strains, causing the stress-strain curve to become independent of the sample preparation protocol in this regime. In future studies, we will extract the parameters that define the spring network model directly from atomic rearrangements that occur during uniaxial deformation. © 2023, CC BY-NC-ND.

关键词： Metallic glass

Magnetic Exciton-Polariton with Strongly Coupled Atomic and Photonic Anisotropies

学校读者我要写书评

暂无评论

arXiv 2023年

作者： Li, Qiuyang Xie, Xin Alfrey, Adam Beach, Christiano W. McLellan, Nicholas Lu, Yang Hu, Jiaqi Liu, Wenhao Dhale, Nikhil Lv, Bing Zhao, Liuyan Sun, Kai Deng, Hui Department of Physics University of Michigan Ann ArborMI48109 United States Applied Physics Program University of Michigan Ann ArborMI48109 United States Department of Electrical Engineering and Computer Science University of Michigan Ann ArborMI48109 United States Department of Physics University of Texas at Dallas RichardsonTX75080 United States

Anisotropy plays a key role in science and engineering. However, the interplay between the material and engineered photonic anisotropies has hardly been explored due to the vastly different length scales. Here we demonstrate a matter-light hybrid system, exciton-polaritons in a 2D antiferromagnet, CrSBr, coupled with an anisotropic photonic crystal (PC) cavity, where the spin, atomic lattice, and photonic lattices anisotropies are strongly correlated, giving rise to unusual properties of the hybrid system and new possibilities of tuning. We show exceptionally strong coupling between engineered anisotropic optical modes and anisotropic excitons in CrSBr, which is stable against excitation densities a few orders of magnitude higher than polaritons in isotropic materials. Moreover, the polaritons feature a highly anisotropic polarization tunable by tens of degrees by controlling the matter-light coupling via, for instance, spatial alignment between the material and photonic lattices, magnetic field, temperature, cavity detuning and cavity quality-factors. The demonstrated system provides a prototype where atomic- and photonic-scale orders strongly couple, opening opportunities of photonic engineering of quantum materials and novel photonic devices, such as compact, on-chip polarized light source and polariton laser. © 2023, CC BY-NC-ND.

关键词： Anisotropy