170,597 results on '"Condensed Matter::Superconductivity"'
Search Results
202. Elucidating the Formation Mechanism of the Vortex at the Ta/Fe Explosively Welded Interface Using Microstructure Characterizations and Numerical Simulations
- Author
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Zhaowu Shen, Daiguo Chen, Honghao Ma, Junfeng Xu, Yang Ming, and Bingyuan Zhang
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Work (thermodynamics) ,Structural material ,Materials science ,Metallurgy ,Metals and Alloys ,Welding ,Mechanics ,Condensed Matter Physics ,Microstructure ,Matrix (geology) ,Vortex ,law.invention ,Mechanics of Materials ,law ,Condensed Matter::Superconductivity ,Extrusion ,Deformation (engineering) - Abstract
The vortex at the Ta/Fe explosively welded interface is featured by the intermediate zone being fully bounded by Ta matrix, which differs from the vortex structures observed in the most bimetallic interfaces. In this work, advanced characterizations and numerical simulations were integrated to establish a detailed evolution model of the special vortex, and the associated governing mechanisms were identified. It was also inferred that the mesoscale cavity and microcracks within the vortex resulted from the geometric hole and extrusion movement that generated during the vortex evolution, respectively. Furthermore, a diversity of metallurgical structure was revealed at the Ta/Fe interface, which did support the deformation path of the interface material observed in the simulations. The insights gathered here benefit an in-depth comprehension of impact welding.
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- 2021
203. Monolithic Three-Dimensional Tuning of an Atomically Defined Silicon Tunnel Junction
- Author
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Matthew Donnelly, Michelle Y. Simmons, JG Joris Keizer, and Yousun Chung
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OR gate ,Materials science ,Silicon ,chemistry.chemical_element ,Bioengineering ,Hardware_PERFORMANCEANDRELIABILITY ,Computer Science::Hardware Architecture ,Computer Science::Emerging Technologies ,Tunnel junction ,Condensed Matter::Superconductivity ,Hardware_INTEGRATEDCIRCUITS ,General Materials Science ,Hardware_ARITHMETICANDLOGICSTRUCTURES ,Quantum information ,Quantum tunnelling ,Capacitive coupling ,business.industry ,Mechanical Engineering ,General Chemistry ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,Condensed Matter Physics ,chemistry ,Logic gate ,Qubit ,Optoelectronics ,business ,Hardware_LOGICDESIGN - Abstract
A requirement for quantum information processors is the in situ tunability of the tunnel rates and the exchange interaction energy within the device. The large energy level separation for atom qubits in silicon is well suited for qubit operation but limits device tunability using in-plane gate architectures, requiring vertically separated top-gates to control tunnelling within the device. In this paper, we address control of the simplest tunnelling device in Si:P, the tunnel junction. Here we demonstrate that we can tune its conductance by using a vertically separated top-gate aligned with ±5 nm precision to the junction. We show that a monolithic 3D epitaxial top-gate increases the capacitive coupling by a factor of 3 compared to in-plane gates, resulting in a tunnel barrier height tunability of 0-186 meV. By combining multiple gated junctions in series we extend our monolithic 3D gating technology to implement nanoscale logic circuits including AND and OR gates.
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- 2021
204. Phase-Field Simulation of Superconductor-Ferromagnet Bilayer-Based Cryogenic Strain Sensor
- Author
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Houbing Huang, Chao Yang, Xiaoming Shi, Muhammad Sulaman, Jing Wang, and Hasnain Mehdi Jafri
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Superconductivity ,Work (thermodynamics) ,Materials science ,Condensed matter physics ,Bilayer ,Phase (waves) ,Conductivity ,Condensed Matter Physics ,Electronic, Optical and Magnetic Materials ,Condensed Matter::Materials Science ,Transducer ,Ferromagnetism ,Condensed Matter::Superconductivity ,Ground state - Abstract
Hybrid superconductor-ferromagnet materials have gained huge attention due to their opposite nature of electronic states, bringing up new properties and applications when coupled together. Cryogenic sensors and memories research significantly lag behind their conventional counterparts. Here, we investigated numerically the strain/motion sensing ability of superconductor-ferromagnet bilayer using Ginzburg–Landau equations for superconductivity and Landau-Lifshitz-Gilbert equations for ferromagnetism. Clear segregation of average carrier concentration of the superconductor layer, which defines its conductivity, was observed with various magnitudes of strain (i.e. 0%, 1%, and 5%). The current purge was used to bring the designed sensor to its ground state, whereas the sensor retained the information on the amount of strain for the extended period unless reset (by the current purge) for reuse. This work opens up a new direction for superconductor-ferromagnet bilayer device applications towards strain/motion sensors and/or transducers.
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- 2021
205. Creep Behavior of Saturated Clay in Triaxial Test and a Hyperbolic Model
- Author
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Yuke Lu, Xiao Bin, Zhou Peijiao, Hu Minyun, and Zhang Yong
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QE1-996.5 ,Materials science ,Article Subject ,Stress path ,Effective stress ,Geology ,Triaxial shear test ,Physics::Geophysics ,Stress (mechanics) ,Shear (sheet metal) ,Superposition principle ,Linear relationship ,Creep ,Condensed Matter::Superconductivity ,General Earth and Planetary Sciences ,Composite material - Abstract
As one of the basic mechanical properties of soil, the creep property of a given type soil is related to stress path, and stress level. In this paper, triaxial shear creep tests under different deviatoric stress levels were performed on both intact sample and the reconstituted sample of clay taken from Hangzhou, China. Based on the Boltzmann linear superposition principle, the creep curves of the clay sample under different levels of deviatoric stress were obtained, and the creep characteristics of the intact sample and the reconstituted sample were compared in both total stress creep analysis and effective stress creep analysis. Furthermore, the creep curves were fitted using a hyperbolic creep model. The results show that (1) under the same stress level, the creep of intact sample evolves more than that of reconstituted sample; (2) the hyperbolic creep model is suited to describe the creep characteristics of intact and reconstituted clay, and the model parameters A s and B s can be linearly correlated to the stress level D r ; (3) for the application of the hyperbolic model, the total stress analysis works better, and the model parameters A s and B s can be determined by a linear relationship with Dr.
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- 2021
206. Multiterminal Inverse AC Josephson Effect
- Author
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Takashi Taniguchi, Lingfei Zhao, Ethan G. Arnault, Sara Idris, Kenji Watanabe, Andrew Seredinski, Trevyn Larson, Ivan V. Borzenets, Francois Amet, Gleb Finkelstein, and Aeron McConnell
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Coupling ,Physics ,Superconductivity ,Josephson effect ,Condensed matter physics ,Mechanical Engineering ,Phase (waves) ,Bioengineering ,02 engineering and technology ,General Chemistry ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Condensed Matter::Superconductivity ,Phase space ,0103 physical sciences ,General Materials Science ,010306 general physics ,0210 nano-technology ,Microwave ,Curse of dimensionality ,Voltage - Abstract
When a Josephson junction is exposed to microwave radiation, it undergoes the inverse AC Josephson effect─the phase of the junction locks to the drive frequency. As a result, the I-V curves of the junction acquire "Shapiro steps" of quantized voltage. If the junction has three or more superconducting contacts, coupling between different pairs of terminals must be taken into account and the state of the junction evolves in a phase space of higher dimensionality. Here, we study the multiterminal inverse AC Josephson effect in a graphene sample with three superconducting terminals. We observe robust fractional Shapiro steps and correlated switching events, which can only be explained by considering the device as a completely connected Josephson network. We successfully simulate the observed behaviors using a modified two-dimensional RCSJ model. Our results suggest that multiterminal Josephson junctions are a playground to study highly connected nonlinear networks with novel topologies.
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- 2021
207. On desingularization of steady vortex for the lake equations
- Author
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Weicheng Zhan, Daomin Cao, and Changjun Zou
- Subjects
Physics ,Condensed Matter::Superconductivity ,Applied Mathematics ,Mechanics ,Vortex - Abstract
In this paper, we constructed a family of steady vortex solutions for the lake equations with a general vorticity function, which constitutes a desingularization of a singular vortex. The precise localization of the asymptotic singular vortex is shown to be the deepest position of the lake. We also study global nonlinear stability for these solutions. Some qualitative and asymptotic properties are also established.
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- 2021
208. Effect of Molecular Chain Mobility Induced by High-Pressure CO2 on Crystallization Memory Behavior of Poly(<scp>d</scp>-lactic Acid)
- Author
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Guangxian Li, Xia Liao, Suilin Liu, Feng Liu, and Shaojie Li
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Materials science ,Crystallization of polymers ,Physics::Optics ,General Chemistry ,Condensed Matter Physics ,Lactic acid ,law.invention ,Memory behavior ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,Chain (algebraic topology) ,Homogeneous ,law ,Condensed Matter::Superconductivity ,High pressure ,General Materials Science ,Astrophysics::Earth and Planetary Astrophysics ,Crystallization ,Physics::Atmospheric and Oceanic Physics - Abstract
Recently, the homogeneous crystallization of polymers under CO2 has been investigated systematically, while the effect of CO2 on heterogeneous crystallization such as crystallization memory effect ...
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- 2021
209. Effective Behaviors of Graded Thermoelectric Material under Thermal Shock
- Author
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Sheng-Hu Ding and Hai-Liang Ma
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Thermal shock ,Materials science ,Solid-state physics ,Energy conversion efficiency ,Mechanics ,Condensed Matter Physics ,Thermoelectric materials ,Functionally graded material ,Computer Science::Other ,Electronic, Optical and Magnetic Materials ,Condensed Matter::Materials Science ,Superposition principle ,Condensed Matter::Superconductivity ,Thermoelectric effect ,Materials Chemistry ,Condensed Matter::Strongly Correlated Electrons ,Electrical and Electronic Engineering ,Physical quantity - Abstract
Introducing functional gradients into thermoelectric materials can affect their conversion efficiency and mechanical properties. In this paper, the problem of thermal shock of an exponentially thermoelectric graded material is considered. Using the superposition principle and the method of separation of variables, expressions for the temperature and other physical quantities of the thermoelectric field are obtained. Then, other physical expressions for the thermoelectric field are derived from the expression for temperature. The effective thermoelectric coefficients of a static functionally graded material are obtained by using the equivalence principle. The numerical results describe the changes of physical quantities related to temperature with time and position. Meanwhile, the basic condition for thermoelectric conversion is analyzed based on the thermoelectric figure of merit, thermoelectric conversion efficiency, effective thermoelectric coefficient, and effective thermoelectric figure of merit. The results show that higher thermoelectric conversion efficiency can be achieved by changing the grading parameters. These results provide a theoretical basis for the production and performance optimization of thermoelectric materials.
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- 2021
210. Numerical Analysis of Gravitational Vortex Chamber
- Author
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Shahadat Hossain Zehad, Ing. Irfan Ahmed, Md. Redwan Islam, and Sadman Al Faiyaz
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Physics::Fluid Dynamics ,Gravitation ,Physics ,Condensed Matter::Superconductivity ,Numerical analysis ,Mechanics ,Vortex - Abstract
A rotating mass of fluid is known as vortex and the motion of the rotating mass of fluid is known as vortex motion. Vorticity is the circulation per unit area. In this research simulation of a vortex chamber is to be carried out in ANSYS CFD taking water as fluid domain for generating a water vortex that is capable enough to move a turbine for electricity generation. The CAD modelling of the setup was set down and simulation was done in fine mesh by taking suitable wall function in the model of a cylindrical chamber along with a rectangular channel with a contraction portion at the end of it where good amount of vortex generation was acquired by observing velocity and pressure by setting different parameters. The results shows the pressure and velocity contours with 3D velocity streamline flow and the curve of the velocity and pressure curve shows the decrease of pressure and increase of velocity from inlet to outlet that leads to a decent vortex generation.
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- 2021
211. High-Throughput Screening of Quaternary Compounds and New Insights for Excellent Thermoelectric Performance
- Author
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Jun-Ming Liu, Aijun Hong, and Yuxia Tang
- Subjects
Materials science ,High-throughput screening ,FOS: Physical sciences ,Nanotechnology ,Applied Physics (physics.app-ph) ,Physics - Applied Physics ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Condensed Matter::Materials Science ,General Energy ,Condensed Matter::Superconductivity ,Thermoelectric effect ,Condensed Matter::Strongly Correlated Electrons ,Physical and Theoretical Chemistry - Abstract
It is well known that the high electric conductivity, large Seebeck coefficient, and low thermal conductivity are preferred for enhancing thermoelectric performance, but unfortunately, these properties are strongly inter-correlated with no rational scenario for their efficient decoupling. This big dilemma for thermoelectric research appeals for alternative strategic solutions, while the high-throughput screening is one of them. In this work, we start from total 3136 real electronic structures of the huge X2YZM4 quaternary compound family and perform the high-throughput searching in terms of enhanced thermoelectric properties. The comprehensive data-mining allows an evaluation of the electronic and phonon characteristics of those promising thermoelectric materials. More importantly, a new insight that the enhanced thermoelectric performance benefits substantially from the coexisting quasi-Dirac and heavy fermions plus strong optical-acoustic phonon hybridization, is proposed. This work provides a clear guidance to theoretical screening and experimental realization and thus towards development of performance-excellent thermoelectric materials.
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- 2021
212. Initial Stages of Oxide Formation on Copper Surfaces during Oxygen Bombardment at Room Temperature
- Author
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Robert Peter and Mladen Petravic
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Materials science ,Inorganic chemistry ,Kinetics ,Oxide ,chemistry.chemical_element ,Copper ,Oxygen ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Metal ,Condensed Matter::Materials Science ,chemistry.chemical_compound ,General Energy ,chemistry ,Condensed Matter::Superconductivity ,visual_art ,visual_art.visual_art_medium ,Physics::Accelerator Physics ,Astrophysics::Earth and Planetary Astrophysics ,Physics::Chemical Physics ,Physical and Theoretical Chemistry - Abstract
We have studied the oxidation kinetics of initial stages of oxide formation on clean metallic copper surfaces during low-energy O2+ bombardment at room temperature using X-ray photoelectron spectro...
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- 2021
213. Growth of Open Honeycomb-like Sn Structures on Ag(111) at Low Temperatures
- Author
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J. D. Fuhr, Hugo Ascolani, and J. E. Gayone
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Materials science ,Molecular physics ,Honeycomb like ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,law.invention ,Condensed Matter::Materials Science ,General Energy ,Electron diffraction ,law ,Condensed Matter::Superconductivity ,Density functional theory ,Physical and Theoretical Chemistry ,Scanning tunneling microscope - Abstract
We studied, with a combination of low-energy electron diffraction (LEED) and scanning tunneling microscopy (STM) experiments and density functional theory (DFT) calculations, the growth of Sn depos...
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- 2021
214. In situ SR-CT Experimental Study on the Directional Sintering of High-Temperature Superconductor YBCO Materials in the Microwave Fields
- Author
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Yongcun Li, Xingyi Zhang, Lei Shen, Feng Xu, Yu Xiao, Yuanjie Wang, Liangyuan Wang, and Xiaofang Hu
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Superconductivity ,Electromagnetic field ,Grain growth ,Materials science ,Condensed matter physics ,Condensed Matter::Superconductivity ,Electric field ,Metals and Alloys ,Particle ,Sintering ,Microstructure ,Industrial and Manufacturing Engineering ,Microwave - Abstract
YBa2Cu3O7-x (YBCO) is a kind of high-temperature superconducting material that has important application in information, energy, medical treatment, etc., and the superconducting properties of YBCO are closely related to its internal microstructure. In this study, the microwave heating method was adopted to prepare the YBCO materials. The internal 3D online evolution observation based on the synchrotron radiation computed tomography technology shows that there was directional grain growth phenomenon of YBCO during microwave sintering process. In local regions with special microstructure, these particles grew to the same point. Here, the theoretical models of single and multiple particles in the microwave electromagnetic fields were established. Based on these theoretical models and finite element analysis, it shows that the YBCO particles can modulate the distribution of electromagnetic fields, resulting in the significantly higher electric field intensity at the particle junctions than other regions. Moreover, there were very high electric field intensity and temperature gradients in the directions of particle growth. These factors were crucial in directional sintering. These results will provide theoretical basis and technical guidance for the controllable preparation and performance optimization of the internal microstructure of superconducting materials in the preparation process.
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- 2021
215. Heat Capacity and Susceptibility of Rare Earth Magnetic Superconductors
- Author
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Salila Das, Prabir K. Mukherjee, and Preeti Suman Dash
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Superconductivity ,Physics ,Condensed matter physics ,Specific heat ,Normal phase ,Rare earth ,Context (language use) ,Condensed Matter Physics ,Heat capacity ,Electronic, Optical and Magnetic Materials ,Condensed Matter::Superconductivity ,Phase (matter) ,Antiferromagnetism ,Condensed Matter::Strongly Correlated Electrons - Abstract
We calculate the specific heat and susceptibility of rare earth magnetic superconductors in the context of the Ginzburg–Landau theory. The specific heat and susceptibility are calculated at both the coexistence phase of antiferromagnetism and superconductivity and normal phase. Theoretical results are compared with experimental results which agree excellently well.
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- 2021
216. Applied Superconductivity and Electromagnetic Devices - Principles and Current Exploration Highlights
- Author
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Jun Zheng, Guang Sheng, Jiamin Zhu, Weihua Zhang, Qiang Li, Jianguo Zhu, Jianhua Wang, Boyang Shen, Zigang Deng, Li Ren, Tim Coombs, Ying Xu, Jing Shi, Jian Xun Jin, Yanfang Bi, Xiaolong Liu, Yuntao Song, Yuejin Tang, Xin Chen, Md. Rabiul Islam, Yong Zhao, Bin Xiang, and Youguang Guo
- Subjects
Physics ,Superconductivity ,General Physics ,Tokamak ,High-temperature superconductivity ,Superconducting magnet ,Condensed Matter Physics ,Engineering physics ,Electronic, Optical and Magnetic Materials ,law.invention ,Characterization (materials science) ,0204 Condensed Matter Physics, 0906 Electrical and Electronic Engineering, 0912 Materials Engineering ,law ,Electromagnetic coil ,Condensed Matter::Superconductivity ,Electrical and Electronic Engineering ,Electrical conductor ,Magnetic levitation - Abstract
With regard to the state-of-the-art technologies in the fields of applied superconductivity and electromagnetic devices, research and development highlights are presented. The recent progress and achievement described with principle and technical details include mainly i) applied superconducting materials; ii) superconducting magnets and their applications such as in ITER and Tokamaks; iii) high T c superconducting (HTS) magnetic levitation and applications; iv) HTS smart grids; v) superconducting and electromagnetic material modelling and characterization; and vi) advanced electromagnetic devices. The applied superconductivity technology and availability are especially focused and verified with the trend of development prospection.
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- 2021
217. Local spin-triplet superconductivity in half-metallic manganites: A perspective platform for high-temperature topological superconductivity
- Author
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V. N. Krivoruchko
- Subjects
Superconductivity ,Physics ,Nanostructure ,Physics and Astronomy (miscellaneous) ,General Physics and Astronomy ,Theoretical research ,Topology ,Manganite ,Metal ,Condensed Matter::Superconductivity ,Pairing ,visual_art ,visual_art.visual_art_medium ,Condensed Matter::Strongly Correlated Electrons ,Symmetry breaking ,Spin-½ - Abstract
Topological materials and their unusual properties are nowadays a focus of experimental and theoretical research. Promising systems where topological superconducting phases can be realized are materials with a spin-triplet superconducting state. Yet, in the nature superconductors with a spin-triplet p-wave pairing are exceptions. The experimentally accessible way to overcome this bottleneck is spin-triplet pairing induced in proximitized structures of spin-singlet superconductors with time-reversal symmetry breaking counterparts. We discuss the possibility of creating such materials using superconductor–half-metallic manganite nano-structures. A unique promising feature of the proximity-coupled hybrid structures is high-temperature local triplet superconductivity in half-metallic manganites. The experimental evidence of a latent spin-triplet pairing in half-metallic manganites is presented and conditions favoring the topological superconducting state in nanostructures based on them are discussed.
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- 2021
218. Intrinsic phonon anharmonicity in heavily doped graphene probed by Raman spectroscopy
- Author
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Yu-Chen Leng, Miao-Ling Lin, Xin Zhang, Ping-Heng Tan, Xin Cong, and Xu Chen
- Subjects
Materials science ,Condensed matter physics ,Phonon ,Graphene ,business.industry ,Fermi level ,Anharmonicity ,General Chemistry ,law.invention ,Condensed Matter::Materials Science ,symbols.namesake ,Graphite intercalation compound ,chemistry.chemical_compound ,Laser linewidth ,Semiconductor ,chemistry ,law ,Condensed Matter::Superconductivity ,symbols ,Condensed Matter::Strongly Correlated Electrons ,General Materials Science ,Physics::Chemical Physics ,Raman spectroscopy ,business - Abstract
The temperature-dependent (T-dependent) linewidth (ΓG) and frequency shift (ΔωG) of the G mode provide valuable information on the phonon anharmonicity of graphene-based materials. In contrast to the negligible contribution from electron-phonon coupling (EPC) to the linewidth of a Raman mode in semiconductors, ΓG in pristine graphene is dominated by EPC contribution at room temperature due to its semimetallic characteristics. This leads to difficulty in resolving intrinsic contribution from phonon anharmonicity to ΓG. Here, we probed the intrinsic phonon anharmonicity of heavily-doped graphene by T-dependent Raman spectra based on FeCl3-based stage-1 graphite intercalation compound (GIC), in which the EPC contribution is negligible due to the large Fermi level (EF) shift. The ΔωG and ΓG exhibit a nonlinear decrease and noticeable broadening with increasing temperature, respectively, which are both dominated by phonon anharmonicity processes. The contribution of phonon anharmonicity to ΓG of heavily-doped graphene decreases as the EF approaches to the Dirac point. However, the T dependence of ΔωG is almost independent on EF and qualitatively agrees with the theoretical result of pristine graphene. These results provide a deeper understanding of the role of phonon anharmonicity on the Raman spectra of heavily doped graphene.
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- 2021
219. PPV and Frequency Characteristics of Tunnel Blast-Induced Vibrations on Tunnel Surfaces and Tunnel Entrance Slope Faces
- Author
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Wang Zeming, Ping Gu, Xiaobo Zhang, Chi Yao, Ting Zhang, and Jianhua Yang
- Subjects
Article Subject ,Computer simulation ,Wave propagation ,Physics ,QC1-999 ,Mechanical Engineering ,Attenuation ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,Geotechnical Engineering and Engineering Geology ,Condensed Matter Physics ,Vibration ,Mechanics of Materials ,Surface wave ,Condensed Matter::Superconductivity ,Geotechnical engineering ,Particle velocity ,Center frequency ,Rock mass classification ,Geology ,Civil and Structural Engineering - Abstract
Tunnel blast-induced vibration probably causes damage to the rock mass surrounding the tunnel surface and also to the rock mass of the slope at the tunnel entrance. It is important to simultaneously monitor the vibration on the tunnel surface and on the tunnel entrance slope face, especially when the blasting work face is close to tunnel entrance. During blasting excavation of the traffic tunnel at Baihetan hydropower station, vibration monitors were installed both on the tunnel surface and on the tunnel entrance slope face. Based on the monitoring data, a comparative study is conducted on the peak particle velocity (PPV) and frequency characteristics of the vibrations at these two locations. A three-dimensional FEM simulation of the tunnel blast is then performed to verify the field test results. The field monitoring and the numerical simulation show that there is significant difference between the vibration on the tunnel surface and that on the tunnel entrance slope face. The vibration on the tunnel surface has greater PPV and faster attenuation, while the tunnel entrance slope face has higher frequency and faster reduction rate in the center frequency. These differences are attributed to the different wave types and wave propagation paths. The tunnel surface is mainly surface waves transmitted through the damaged rock mass around the tunnel profile, while the tunnel entrance slope face originates mainly from the body waves transmitted via the undamaged rock mass inside the mountain. The comparisons of the monitored vibrations with the velocity limits specified in the Chinese standard show that the most dangerous vibration that may exceed the limit occurs on the tunnel surface. Therefore, the maximum charge weight used in the tunnel blast is determined by the vibration on the tunnel surface. Under different control standards, the allowable maximum charge weight per delay is further discussed.
- Published
- 2021
220. Evolution of low-energy magnetic excitations pair spectrum in SmMnO3+δ
- Author
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F. N. Bukhanko and A. F. Bukhanko
- Subjects
Superconductivity ,Physics ,Phase transition ,Physics and Astronomy (miscellaneous) ,Condensed matter physics ,General Physics and Astronomy ,Quantum oscillations ,Landau quantization ,Spinon ,Magnetic field ,Magnetization ,Condensed Matter::Superconductivity ,Condensed Matter::Strongly Correlated Electrons ,Quantum spin liquid - Abstract
The identification of low-energy thermal excitations in SmMnO3+δ degenerate states of spin and superconducting quantum liquids in magnetic fields H ≤ 3.5 kOe is presented. In the temperature interval 4.2–12 K, the Landau quantization of the low-energy magnetic excitations pair spectrum of Z2 quantum spin liquid is found in the system spinon-gauge field. The formation of a broad continuum of spinon pair excitations in the “weak magnetic field” regime (H = 100 Oe, 1 kOe) in the FC regime is explained in the framework of the Landau quantization models of the compressible spinon gas with fractional values of the factor ν filling three overlapping bands. In the regime of “strong magnetic field” (H = 3.5 kOe), the quantum oscillations of temperature dependences of “supermagnetization” of the incompressible spinon liquid were observed. They have the form of three narrow steps (plateaus), corresponding to a complete filling of the non-overlapping Landau bands with integer values of the filling factor by spinons. These results are evidence for the existence of vortex gauge field fluctuations with a high density in the magnetic fields H ≥ 100 Oe. The strong growth of vortex fluctuations can be explained by a second-kind phase transition in SmMnO3+δ in the form of the vortices condensation. Growth of the external dc magnetic field strength in the SmMnO3+δ samples in the interval of fields 0
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- 2021
221. Design and Performance Analyses of Multi-pole HTS Maglev Guideways for the Electromagnetic Launch
- Author
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Jin Fang, Lichao Nie, Xiaodong Li, Yue Wu, and Bin Liu
- Subjects
Materials science ,Superconducting magnet ,Condensed Matter Physics ,Finite element method ,Automotive engineering ,Electronic, Optical and Magnetic Materials ,Magnetic field ,Electromagnetic launch ,Condensed Matter::Superconductivity ,Maglev ,Magnet ,Levitation ,Electrical and Electronic Engineering ,Magnetic levitation - Abstract
A prototype of the high temperature superconducting (HTS) Maglev system for the electromagnetic launch was built in our laboratory. To meet the higher carrying capacity requirement of this practical application, multi-pole permanent-magnet guideways (PMGs) with different flux concentration methods and various arrangement schemes of HTS bulks have been proposed. The magnetic field distribution of these multi-pole PMG with the iron and permanent magnet (PM) concentration schemes has been estimated by employing both analytical and finite element methods. Meanwhile, a two-dimensional simulation model was established to evaluate the levitation and lateral performance of the Maglev system with several arrangement cases of HTS bulks. It has been validated that the total levitation force of the system can be significantly improved by increasing the pole number of the PMG and applying the optimal arrangement scheme.
- Published
- 2021
222. Quench Protection Modeling of an HTS Magnet for MRI System
- Author
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Jie Sheng, Xiao Yuan Chen, Xinsheng Yang, Xintao Zhang, Mengyuan Tian, Zhipeng Ni, Liang Guo, Lei Zeng, Chen Wei, Yi Shi, Jiabin Yang, Boyang Shen, Tim Coombs, Qi Xie, Yavuz Ozturk, Lin Fu, and Huajun Liu
- Subjects
Superconductivity ,Materials science ,High-temperature superconductivity ,Nuclear engineering ,Hot spot (veterinary medicine) ,Superconducting magnet ,Condensed Matter Physics ,Finite element method ,Electronic, Optical and Magnetic Materials ,law.invention ,Magnetic circuit ,law ,Condensed Matter::Superconductivity ,Magnet ,High field ,Electrical and Electronic Engineering - Abstract
The High-temperature Superconducting (HTS) magnet is one of the most promising technologies to accommodate various high field applications. With the high magnetic field, the quench problem of HTS material should be considered with extra care, and the specific quench protection scheme should be projected. In this article, the modeling of the quench protection of an HTS magnet for the MRI system is presented. The modeling strategy was composed of two stages: Stage 1 the HTS magnet was in the normal operation circuit, and Stage 2 the HTS magnet was switched to the heat dissipation circuit. The 1st stage was based on the finite element method (FEM) using the H -formulation together with the thermal-coupled model, which simulated the current distribution of typical HTS tapes and showed the process of temperature increase when the hot source occurred. The 2nd stage was based on the analytical model to investigate the reasonable damping resistance and the hot spot temperature of the HTS magnet.
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- 2021
223. Van der Waals ferromagnetic Josephson junctions
- Author
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Jinshan Yang, Shanshan Liu, Enze Zhang, Pengliang Leng, Yuda Zhang, Zihan Li, Yunkun Yang, Zehao Jia, Xingdan Sun, Tongyao Zhang, Xiaoyi Xie, Shaoming Dong, Zheng Han, Xiangyu Cao, Faxian Xiu, Xufeng Kou, and Linfeng Ai
- Subjects
Josephson effect ,Magnetism ,Science ,General Physics and Astronomy ,FOS: Physical sciences ,Two-dimensional materials ,General Biochemistry, Genetics and Molecular Biology ,Article ,law.invention ,Superconducting properties and materials ,Superconductivity (cond-mat.supr-con) ,symbols.namesake ,Condensed Matter::Materials Science ,law ,Magnetic properties and materials ,Condensed Matter::Superconductivity ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,Physics ,Superconductivity ,Condensed Matter::Quantum Gases ,Multidisciplinary ,Condensed matter physics ,Condensed Matter - Mesoscale and Nanoscale Physics ,Condensed Matter - Superconductivity ,Heterojunction ,General Chemistry ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,Magnetic field ,SQUID ,Ferromagnetism ,Superconducting devices ,symbols ,Condensed Matter::Strongly Correlated Electrons ,van der Waals force - Abstract
Superconductor-ferromagnet interfaces in two-dimensional heterostructures present a unique opportunity to study the interplay between superconductivity and ferromagnetism. The realization of such nanoscale heterostructures in van der Waals (vdW) crystals remains largely unexplored due to the challenge of making atomically-sharp interfaces from their layered structures. Here, we build a vdW ferromagnetic Josephson junction (JJ) by inserting a few-layer ferromagnetic insulator Cr2Ge2Te6 into two layers of superconductor NbSe2. The critical current and corresponding junction resistance exhibit a hysteretic and oscillatory behavior against in-plane magnetic fields, manifesting itself as a strong Josephson coupling state. Also, we observe a central minimum of critical current in some JJ devices as well as a nontrivial phase shift in SQUID structures, evidencing the coexistence of 0 and π phase in the junction region. Our study paves the way to exploring sensitive probes of weak magnetism and multifunctional building-blocks for phase-related superconducting circuits using vdW heterostructures., The superconductor-ferromagnet interface provides a unique opportunity to study the interplay between superconductivity and ferromagnetism. Here, the authors build a van der Waals ferromagnetic Josephson junction evidencing a strong 0 and π phase Josephson coupling.
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- 2021
224. Analysis on the Effect of Superconductor Layer Thickness on the AC Loss of Conductor on Round Core (CORC) Cables
- Author
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Mengyuan Tian, Chao Li, Jun Ma, Haigening Wei, Jintao Hu, Yavuz Ozturk, Junshi Li, Tim Coombs, Jiabin Yang, and Boyang Shen
- Subjects
Superconductivity ,Power transmission ,CORC ,Materials science ,Multiphysics ,Mechanical engineering ,Superconducting magnet ,Condensed Matter Physics ,Electronic, Optical and Magnetic Materials ,Magnetic field ,law.invention ,Conductor ,law ,Condensed Matter::Superconductivity ,Electrical and Electronic Engineering ,Alternating current ,computer ,computer.programming_language - Abstract
Superconducting Conductor on Round Core (CORC) cables fabricated by several high temperature superconducting (HTS) tapes are able to carry enormous electrical current density, to be widely used in a variety of superconducting applications such as power transmission, fusion, and magnetic resonance imaging (MRI). However, the AC losses induced in the superconducting tapes under alternating current or magnetic field generate heat dissipation which can reduce the electric power efficiency. Therefore, it is essential to analyze the AC loss behavior of CORC cables as well as consider methods to reduce it. This paper presents an AC loss study of CORC cables with several different superconducting layer thicknesses. The CORC cable simulation model is built in a software suite named COMSOL Multiphysics utilising the finite-element method (FEM) solved by the three-dimensional (3-D) H -formulation. By implementing FEM simulations, the cases of increasing the degree of freedom of superconducting layers have been considered, and the AC losses of a single layer CORC cable model with three tapes mounted around the core have been calculated and analyzed for different layer thicknesses. Simulation results are verified with experimental results measured in previous literature.
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- 2021
225. Influence of Electromagnetic Shunt Damper on Nonlinear Vibration of HTS Maglev System
- Author
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Jingzhong Zhao, Li Wang, Haitao Li, Jukun Wang, Zigang Deng, and Shan Wang
- Subjects
Physics ,Condensed Matter Physics ,Electronic, Optical and Magnetic Materials ,Damper ,Vibration ,Nonlinear system ,Shock absorber ,Amplitude ,Control theory ,Condensed Matter::Superconductivity ,Maglev ,Levitation ,Physics::Chemical Physics ,Electrical and Electronic Engineering ,Bifurcation - Abstract
The levitation force in the high temperature superconducting (HTS) maglev system has obvious nonlinear characteristics. When the excitation frequency and amplitude meet certain conditions, nonlinear vibration phenomena such as period-doubling bifurcation would appear. Nonlinear vibration will bring difficulties to dynamic analysis and even affect the safety and comfort of driving. While an electromagnetic shunt damper (EMSD) can effectively reduce the vibration amplitude. This paper analyzes the influence of EMSD on the nonlinear vibration of HTS maglev systems from the perspective of experiments and simulations. Firstly, free vibration and forced vibrations in the resonance interval are tested. Secondly, based on numerical simulations, the vibration response under various excitation was analyzed. The results show that the EMSD can effectively suppress its nonlinear vibration. This research has reference value for the detailed understanding of the dynamic characteristics of the HTS maglev and further vehicle design.
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- 2021
226. Linear and Nonlinear Flow Analysis of Elements of a Supersonic Inlet
- Author
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Rajan Kumar, S. Unnikrishnan, and Nikhil Khobragade
- Subjects
Condensed Matter::Quantum Gases ,geography ,Materials science ,geography.geographical_feature_category ,Flow (psychology) ,Aerospace Engineering ,Mechanics ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,Inlet ,Physics::Fluid Dynamics ,Görtler vortices ,Boundary layer ,Condensed Matter::Superconductivity ,Turbulence kinetic energy ,Physics::Accelerator Physics ,Supersonic speed ,Reynolds-averaged Navier–Stokes equations ,Choked flow - Abstract
Boundary layer development in a supersonic inlet is studied, focusing on the flow over the compression ramp and the ramp–isolator junction. Two designs of the junction, a backward-facing step (BFS)...
- Published
- 2021
227. Design, Manufacture and Performance Evaluation of HTS Electromagnet Wound by YBCO Tape
- Author
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Xinyu Fang, Song Yang, Wenyue Zhang, Wenwu Zhou, Jin Fang, Wenlong Li, and Xinghua Zhang
- Subjects
Electromagnetic field ,Materials science ,Electromagnet ,Mechanical engineering ,Superconducting magnet ,Yttrium barium copper oxide ,Condensed Matter Physics ,Finite element method ,Electronic, Optical and Magnetic Materials ,law.invention ,Magnetic field ,Condensed Matter::Soft Condensed Matter ,chemistry.chemical_compound ,chemistry ,law ,Condensed Matter::Superconductivity ,Heat generation ,Electrical and Electronic Engineering ,Suspension (vehicle) - Abstract
Heat generation and serious energy consumption of normal-conductive suspension electromagnets influence the performance and stability of suspension systems. With the development of second generation (2G) high temperature superconducting (HTS) technologies, HTS suspension electromagnets are being considered for energy saving purpose. In this paper, a suspension system with three suspension electromagnets is designed, which is comprised of two normal-conductive suspension electromagnets and a 2G-HTS suspension electromagnet. A three-dimensional (3D) electromagnetic field simulation based on finite element method (FEM) is carried out, and the force test platform of suspension electromagnet is built for performance evaluation of the HTS suspension electromagnet. The experimental results show that the current of HTS suspension electromagnet is steady loaded from 0 A to 70 A under 77 K working conditions, with the suspension force meet the requirements. This work provides a certain theoretical and practical foundation for the future superconducting suspension projects.
- Published
- 2021
228. Rate-dependent indentation size effect on hardness and creep behavior of a titanium metallization film on alumina substrate
- Author
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Yongsheng Ma, Xuefeng Shu, Shengwang Yu, Wang Yongsheng, Yucheng Wu, Gesheng Xiao, and Xuegang Xing
- Subjects
Mining engineering. Metallurgy ,Materials science ,Characteristic length ,TN1-997 ,Metals and Alloys ,chemistry.chemical_element ,Substrate (electronics) ,Creep ,Nanoindentation ,Strain rate ,Surfaces, Coatings and Films ,Film/substrate system ,Biomaterials ,Strain rate sensitivity ,Condensed Matter::Materials Science ,chemistry ,Condensed Matter::Superconductivity ,Indentation ,Indentation size effect ,Ceramics and Composites ,Composite material ,Displacement (fluid) ,Titanium - Abstract
Nanoindentation tests were performed at room temperature to investigate the indentation size effect (ISE) and creep behavior of a titanium metallization film on alumina substrate. The ISE of hardness was examined at different loading strain rate (LSR). The effects of LSR and penetrating depth on nanoindentation creep were evaluated at the steady creep state. Inverse ISE in titanium film was observed at indentation depth below 200 nm while normal ISE was observed at penetrating depth ranging from 200 nm to 1000 nm. Elastic contact theory and strain gradient plasticity theory were applied to interpret the variation trends of hardness respectively. In addition, the intrinsic hardness and characteristic length were found to be strongly dependent on LSR. Except for creep strain rate, creep displacement and creep stress exponent showed relatively conspicuous correlations to LSR and/or penetrating depths.
- Published
- 2021
229. Two distinct superconducting states controlled by orientations of local wrinkles in LiFeAs
- Author
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Jiangping Hu, Geng Li, Hong-Jun Gao, Li Huang, Qi Zheng, Changqing Jin, Lu Cao, Xiancheng Wang, Hong Ding, Xiao Lin, Guangyang Dai, Shiyu Zhu, Wu Zhou, Yuxin Wang, Fazhi Yang, Wenyao Liu, Kun Jiang, and Lingyuan Kong
- Subjects
Phase transition ,Materials science ,Electronic properties and materials ,Science ,FOS: Physical sciences ,General Physics and Astronomy ,General Biochemistry, Genetics and Molecular Biology ,Article ,law.invention ,Superconducting properties and materials ,Superconductivity (cond-mat.supr-con) ,Physics::Fluid Dynamics ,Condensed Matter - Strongly Correlated Electrons ,Surfaces, interfaces and thin films ,law ,Condensed Matter::Superconductivity ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,Spectroscopy ,Nonlinear Sciences::Pattern Formation and Solitons ,Phase diagram ,Superconductivity ,Multidisciplinary ,Strongly Correlated Electrons (cond-mat.str-el) ,Condensed matter physics ,Condensed Matter - Mesoscale and Nanoscale Physics ,Transition temperature ,Condensed Matter - Superconductivity ,General Chemistry ,Symmetry (physics) ,Vortex ,Nonlinear Sciences::Chaotic Dynamics ,Condensed Matter::Soft Condensed Matter ,Scanning tunneling microscope - Abstract
For iron-based superconductors, the phase diagrams under pressure or strain exhibit emergent phenomena between unconventional superconductivity and other electronic orders, varying in different systems. As a stoichiometric superconductor, LiFeAs has no structure phase transitions or entangled electronic states, which manifests an ideal platform to explore the pressure or strain effect on unconventional superconductivity. Here, we observe two types of superconducting states controlled by orientations of local wrinkles on the surface of LiFeAs. Using scanning tunneling microscopy/spectroscopy, we find type-I wrinkles enlarge the superconducting gaps and enhance the transition temperature, whereas type-II wrinkles significantly suppress the superconducting gaps. The vortices on wrinkles show a C2 symmetry, indicating the strain effects on the wrinkles. By statistics, we find that the two types of wrinkles are categorized by their orientations. Our results demonstrate that the local strain effect with different directions can tune the superconducting order parameter of LiFeAs very differently, suggesting that the band shifting induced by directional pressure may play an important role in iron-based superconductivity., The evolution of superconductivity in LiFeAs with respect to pressure or strain remains elusive. Here, the authors observe different response of superconducting states due to different orientations of local wrinkles on the surface of LiFeAs.
- Published
- 2021
230. Ultrafast Photon-Induced Tunneling Microscopy
- Author
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Klaus Kern, Manish Garg, Yang Luo, and Alberto Martin-Jimenez
- Subjects
Photon ,Physics::Optics ,General Physics and Astronomy ,atomic space−time resolution ,Article ,law.invention ,law ,motion ,Condensed Matter::Superconductivity ,Microscopy ,General Materials Science ,angstrom−femtosecond resolution ,Quantum tunnelling ,ultrafast optical STM techniques ,Physics ,angstrom-femtosecond resolution ,business.industry ,General Engineering ,dynamics ,ultrashort pulses ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,Polarization (waves) ,Laser ,Temporal resolution ,atomic space-time resolution ,Optoelectronics ,Scanning tunneling microscope ,4D tunneling microscopy ,business ,Ultrashort pulse - Abstract
Unification of the techniques of ultrafast science and scanning tunneling microscopy (STM) has the potential of tracking electronic motion in molecules simultaneously in real space and real time. Laser pulses can couple to an STM junction either in the weak-field or in the strong-field interaction regime. The strong-field regime entails significant modification (dressing) of the tunneling barrier of the STM junction, whereas the weak-field or the photon-driven regime entails perturbative interaction. Here, we describe how photons carried in an ultrashort pulse interact with an STM junction, defining the basic fundamental framework of ultrafast photon-induced tunneling microscopy. Selective dipole coupling of electronic states by photons is shown to be controllable by adjusting the DC bias at the STM junction. An ultrafast tunneling microscopy involving photons is established. Consolidation of the technique calls for innovative approaches to detect photon-induced tunneling currents at the STM junction. We introduce and characterize here three techniques involving dispersion, polarization, and frequency modulation of the laser pulses to lock-in detect the laser-induced tunneling current. We show that photon-induced tunneling currents can simultaneously achieve angstrom scale spatial resolution and sub-femtosecond temporal resolution. Ultrafast photon-induced tunneling microscopy will be able to directly probe electron dynamics in complex molecular systems, without the need of reconstruction techniques.
- Published
- 2021
231. Dirac Cone Characteristics of Hexachiral Phononic Crystal
- Author
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CHEN Luyun, WANG Jian, CUI Yifeng, KONG Hui
- Subjects
directional band gap ,Chemical engineering ,linear dispersion ,Condensed Matter::Superconductivity ,band structure ,phononic crystal ,Naval architecture. Shipbuilding. Marine engineering ,VM1-989 ,TP155-156 ,TA1-2040 ,dirac cone ,Engineering (General). Civil engineering (General) - Abstract
The band structure properties of phononic crystal is important to evaluate the vibration and noise reduction of acoustic metamaterials. Taking the 2D hexachiral phononic crystal as an example, the band structure and Dirac cone properties were investigated by numerical analysis, and the four-fold accidental degenerate Dirac point was obtained in the center of Brillouin zone. By adjusting the design parameters of ligament structure, a double Dirac cone was broken and a novel directional band gap was formed. The influence of geometric parameters on the directional band gaps width was investigated, and the band structure inversion problem was further discussed. This research can provide support for the application of hexachiral phononic crystal in elastic wave manipulation and acoustic topological insulator.
- Published
- 2021
232. Toward Bright Mid-Infrared Emitters: Thick-Shell n-Type HgSe/CdS Nanocrystals
- Author
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Christopher Melnychuk, Ananth Kamath, and Philippe Guyot-Sionnest
- Subjects
Photoluminescence ,Chemistry ,Condensed Matter::Other ,Doping ,Quantum yield ,General Chemistry ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,Biochemistry ,Molecular physics ,Catalysis ,Article ,Wavelength ,Condensed Matter::Materials Science ,Colloid and Surface Chemistry ,Nanocrystal ,Quantum dot ,Condensed Matter::Superconductivity ,Condensed Matter::Strongly Correlated Electrons ,Absorption (electromagnetic radiation) ,Excitation - Abstract
A procedure is developed for the growth of thick, conformal CdS shells that preserve the optical properties of 5 nm HgSe cores. The n-doping of the HgSe/CdS core/shell particles is quantitatively tuned through a simple postsynthetic Cd treatment, while the doping is monitored via the intraband optical absorption at 5 μm wavelength. Photoluminescence lifetime and quantum yield measurements show that the CdS shell greatly increases the intraband emission intensity. This indicates that decoupling the excitation from the environment reduces the nonradiative recombination. We find that weakly n-type HgSe/CdS are the brightest solution-phase mid-infrared chromophores reported to date at room temperature, achieving intraband photoluminescence quantum yields of 2%. Such photoluminescence corresponds to intraband lifetimes in excess of 10 ns, raising important questions about the fundamental limits to achievable slow intraband relaxation in quantum dots.
- Published
- 2021
233. Analysis and Design of a 100 kA HTS Current Lead for CFETR
- Author
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Liu Chenglian, Yuntao Song, Fuchao He, Huajun Liu, and Kaizhong Ding
- Subjects
Work (thermodynamics) ,Materials science ,Mass flow ,Nuclear engineering ,Overheating (economics) ,Superconducting magnet ,Condensed Matter Physics ,Electronic, Optical and Magnetic Materials ,Thermal conductivity ,Condensed Matter::Superconductivity ,Heat exchanger ,Electrical and Electronic Engineering ,Current (fluid) ,Thermal analysis - Abstract
High temperature superconductors have zero resistance under critical temperature and the HTS tapes have low thermal conductivity. The China Fusion Engineering Test Reactor(CFETR) project requires current leads with current carrying capacity up to 100 kA, making high temperature superconducting current leads the ideal choice. The main work of this paper is the theoretical analysis and optimization design of the 100 kA HTS current lead. Current leads are designed to minimize heat leakage to the cryogenic system and to reduce the mass flow of cooling gas. In this paper, some important design parameters are introduced firstly, and then one dimensional thermal analysis is carried out for the heat exchanger and high temperature superconductor parts. The LOFA time and overheating time of the current lead were calculated through simulation, and it was verified that the design meets the requirements of the project. Finally, the factors that have great influence on the performance of current leads are analyzed. In view of the four influencing factors, which are joint resistance, GHe inlet temperature, hPw and RRR, we respectively produced an optimized design.
- Published
- 2021
234. The Structure and Heat Leakage of MgB2 Superconducting Current Lead
- Author
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Xudong Wang, Zhiyong Shu, Fuming Lu, Wenqing Liang, and Gang Lei
- Subjects
Superconductivity ,Materials science ,Nuclear engineering ,Cryogenics ,Yttrium barium copper oxide ,Condensed Matter Physics ,Thermal conduction ,Electronic, Optical and Magnetic Materials ,chemistry.chemical_compound ,chemistry ,Condensed Matter::Superconductivity ,Heat transfer ,Magnesium diboride ,Electrical and Electronic Engineering ,Joule heating ,Leakage (electronics) - Abstract
In superconducting system, current lead connecting cryogenic device and normal temperature copper cable is the main leakage heat source of entire system. Its performance directly affects cooling cost of cryogenic system. Multi-current leads have advantages of eliminating Joule heat and reducing heat conduction leakage. As a commonly superconducting material, MgB2(magnesium diboride) has broad application prospects. In this paper, the current lead of 200 A MgB2 cable and normal temperature copper cable are designed and calculated. The heat transfer power of superconducting section and the conventional current lead section are 17.90 W and 18 W, respectively. The numerical simulation method is used to verify and analyze calculation results. The temperature at interface between normal temperature copper wire and current lead is lower than 70 K.
- Published
- 2021
235. Effect of Physical Properties of a Gas on the Refrigeration Temperature Drop of Vortex Tubes Used in Oil and Gas Fields
- Author
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Zhang Chengbin, Hu Yaoqiang, Yu Weng, Yulong Wang, Duo Zhang, He Peng, Ai Xinyu, and Yuru Liang
- Subjects
Vortex tube ,Materials science ,business.industry ,Physics::Instrumentation and Detectors ,General Chemical Engineering ,Drop (liquid) ,Fossil fuel ,General Chemistry ,Mechanics ,Article ,Physics::Fluid Dynamics ,Chemistry ,Condensed Matter::Superconductivity ,Refrigeration temperature ,business ,QD1-999 - Abstract
The composition of natural gas can vary considerably across different oil and gas fields. Such compositional variation is primarily reflected in the distinctive physical properties of natural gas. However, during practical application in an oil and gas field, a refrigeration temperature drop in a vortex tube is often observed because vortex tubes generally have low intrinsic refrigeration efficiencies. When vortex tubes are applied in oil and gas fields, the utilization of the oil pressure of a natural gas wellhead is often desirable to avoid excessive energy usage from external devices. In this study, a numerical model of a vortex tube was developed, executed, and validated through laboratory experiments. The refrigeration temperature drop values of 12 gases with distinctive physical properties at a total inlet pressure of 0.3 MPa, an inlet temperature of 300 K, and a cooling mass flow ratio of 0.5 were analyzed. The importance of different physical properties was ranked based on the gray correlation method. Additionally, the synergetic effects of the physical properties on the refrigeration temperature drop were analyzed via regression fitting. The results indicate a significant impact of the gas physical properties on the refrigeration temperature drop in the vortex tube. The maximum and minimum refrigeration temperature drop obtained for different gases can differ by up to 16 K. Furthermore, the refrigeration temperature drop in the vortex tube does not change monotonically with any physical property. Instead, it depends on the synergetic effect from the physical properties, which have different levels of influence on it.
- Published
- 2021
236. The Novel Low Reluctance Superconducting Permanent Magnet Linear Generator for Oceanic Wave Energy Extraction
- Author
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Wei Xu, Omar Farrok, Selim Molla, and Md. Rabiul Islam
- Subjects
Materials science ,Magnetic reluctance ,Stator ,Mechanical engineering ,Superconducting magnet ,Copper conductor ,engineering.material ,Condensed Matter Physics ,Electronic, Optical and Magnetic Materials ,Magnetic field ,law.invention ,Magnetic core ,law ,Condensed Matter::Superconductivity ,Linear congruential generator ,Magnet ,engineering ,Electrical and Electronic Engineering - Abstract
In this paper, the low reluctance superconducting direct drive linear generator (DDLG) for harvesting oceanic wave is presented. At first, a permanent magnet DDLG is designed in the ANSYS/Maxwell environment. The DDLG with both the copper and superconducting winding are characterized with finite element analysis. The DDLG is analyzed with the conventional and recently developed M5 Carlite magnetic cores. High graded neodymium iron boron permanent magnet, N46SH is selected for the DDLG to create strong magnetic field. It is analyzed that the proposed superconducting DDLG with M5 Carlite magnetic core and N46SH permanent magnet produces 294 kW more electrical power compared to that of the DDLG with copper conductor. It is also found that the stator size of the proposed DDLG is much smaller than the conventional one for designing the winding with superconducting tape.
- Published
- 2021
237. Investigation on the air-core vortex in a vertical hydraulic intake system
- Author
-
Lian Shen, Congbin Huang, Dan Zi, Fujun Wang, and Chaoyue Wang
- Subjects
Convection ,Sump ,060102 archaeology ,Vortex Formation ,Renewable Energy, Sustainability and the Environment ,020209 energy ,Multiphase flow ,06 humanities and the arts ,02 engineering and technology ,Mechanics ,Flow pattern ,Vortex ,Physics::Fluid Dynamics ,Condensed Matter::Superconductivity ,0202 electrical engineering, electronic engineering, information engineering ,Air core ,0601 history and archaeology ,Mean flow ,Physics::Atmospheric and Oceanic Physics ,Geology - Abstract
Air-core vortex occurred at the hydraulic intakes deteriorates the performance and operation stability of hydraulic machineries. To investigate the evolution process and generation mechanism of the air-core vortex formed at the vertical intake, large-eddy simulation with the coupled level-set and volume-of-fluid method is performed in a pump sump. This paper elucidates the evolution of velocity distribution caused by pump suction, and associations between vortices motions and velocity evolution and the accompanying free-surface deformations are clarified, which reveals the generation mechanism and evolution characteristics of air-core vortex. Vortices are created by the disturbances of small recirculation zone around the intake pipe. The recirculation is caused by the interaction of the wall of vertical pipe and converging flows with opposite directions driven by the pump suction. The enhancement of vortices due to vortex distortion dominates the air-core vortex formation, and the vertical stretching effect accounts for about 70%. The meandering characteristics of air-core vortex are characterized through analyses of meandering scope and velocity distribution, and the convection of mean flow and sump wall take the leading role in causing its meandering.
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- 2021
238. Mn-Doped Quinary Ag–In–Ga–Zn–S Quantum Dots for Dual-Modal Imaging
- Author
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Raphaël Schneider, Bolat Uralbekov, Perizat Galiyeva, Jordane Jasniewski, Halima Alem, Sébastien Leclerc, Sébastien Blanchard, Hervé Rinnert, Ghouti Medjahdi, Sabine Bouguet-Bonnet, Lavinia Balan, Laboratoire Réactions et Génie des Procédés (LRGP), Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), Institut Jean Lamour (IJL), Université de Lorraine (UL)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Cristallographie, Résonance Magnétique et Modélisations (CRM2), Laboratoire Énergies et Mécanique Théorique et Appliquée (LEMTA ), Conditions Extrêmes et Matériaux : Haute Température et Irradiation (CEMHTI), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université d'Orléans (UO), Institut Parisien de Chimie Moléculaire (IPCM), Chimie Moléculaire de Paris Centre (FR 2769), Institut de Chimie du CNRS (INC)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Ecole Nationale Supérieure de Chimie de Paris - Chimie ParisTech-PSL (ENSCP), Université Paris sciences et lettres (PSL)-Ecole Superieure de Physique et de Chimie Industrielles de la Ville de Paris (ESPCI Paris), Université Paris sciences et lettres (PSL)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de Chimie du CNRS (INC)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Ingénierie des Biomolécules (LIBio), Université de Lorraine (UL), Al-Farabi Kazakh National University [Almaty] (KazNU), IMPACT Biomolécules, and ANR-15-IDEX-0004,LUE,Isite LUE(2015)
- Subjects
Materials science ,General Chemical Engineering ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,Article ,[SPI.MECA.MEFL]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Fluids mechanics [physics.class-ph] ,Condensed Matter::Materials Science ,Semiconductor quantum dots ,Transition metal ,Condensed Matter::Superconductivity ,Mn doped ,QD1-999 ,business.industry ,Doping ,Quinary ,General Chemistry ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Dual (category theory) ,[CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry ,Chemistry ,Modal ,Quantum dot ,Optoelectronics ,Condensed Matter::Strongly Correlated Electrons ,0210 nano-technology ,business - Abstract
International audience; Doping of transition metals within a semiconductor quantum dot (QD) has a high impact on the optical and magnetic properties of the QD. In this study, we report the synthesis of Mn 2+-doped Ag−In−Ga−Zn−S (Mn:AIGZS) QDs via thermolysis of a dithiocarbamate complex of Ag + , In 3+ , Ga 3+ , and Zn 2+ and of Mn(stearate) 2 in oleylamine. The influence of the Mn 2+ loading on the photoluminescence (PL) and magnetic properties of the dots are investigated. Mn:AIGZS QDs exhibit a diameter of ca. 2 nm, a high PL quantum yield (up to 41.3% for a 2.5% doping in Mn 2+), and robust photo-and colloidal stabilities. The optical properties of Mn:AIGZS QDs are preserved upon transfer into water using the glutathione tetramethylammonium ligand. At the same time, Mn:AIGZS QDs exhibit high relaxivity (r 1 = 0.15 mM −1 s −1 and r 2 = 0.57 mM −1 s −1 at 298 K and 2.34 T), which shows their potential applicability for bimodal PL/magnetic resonance imaging (MRI) probes.
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- 2021
239. Influence of external microwave radiation on transport characteristics of superconducting MoRe-Si(W)-MoRe junctions
- Author
-
V. E. Shaternik, O. O. Boliasova, A. P. Shapovalov, and A. Yu. Suvorov
- Subjects
Josephson effect ,Superconductivity ,Work (thermodynamics) ,Materials science ,Physics and Astronomy (miscellaneous) ,business.industry ,General Physics and Astronomy ,Electromagnetic radiation ,Core (optical fiber) ,Condensed Matter::Superconductivity ,Microwave irradiation ,Optoelectronics ,business ,Microwave ,Voltage - Abstract
Specific response of superconducting devices to electromagnetic radiation is a core phenomenon for various applications, ranging from the voltage standard to single photon detectors. One of such effects is the stimulation of the superconductivity itself by microwaves. In the work, we have investigated the impact of external microwave irradiation on the stair-step current-voltage characteristics of MoRe–Si(W)–MoRe Josephson junctions arisen due to phase-slip events in the studied samples. At frequencies above a threshold value, we have observed the stimulation effect that can be explained by a non-equilibrium redistribution of filled energy levels in W clusters. In conclusion, we discuss the main tasks for future research.
- Published
- 2021
240. An Optimal Direct Torque Control Strategy for Surface-Mounted Permanent Magnet Synchronous Motor Drives
- Author
-
Abd Ur Rehman, Han Ho Choi, and Jin-Woo Jung
- Subjects
Lyapunov function ,Computer science ,Stator ,Feed forward ,Optimal control ,Computer Science Applications ,law.invention ,symbols.namesake ,Direct torque control ,Control and Systems Engineering ,Control theory ,law ,Condensed Matter::Superconductivity ,symbols ,Torque ,Transient response ,Electrical and Electronic Engineering ,Stationary Reference Frame ,Information Systems - Abstract
This article investigates an observer-based optimal direct torque control (DTC) strategy for improving the transient and steady-state performance of surface-mounted permanent magnet synchronous motor (SPMSM) drives. Unlike conventional DTC techniques, the proposed method simultaneously controls speed, torque, and flux variables by employing the optimal control theory in the stationary reference frame. This helps achieving a simple structure along with good low-speed operation as the stator flux angle need not be estimated. Further, the feedforward control terms are designed to compensate for system uncertainties. Additionally, an in-depth stability analysis is presented through the Lyapunov theory. Comparative results via a real-time prototype SPMSM test-bed with TI-TMS320F28335 DSP indicate improved performance of the proposed optimal DTC compared to conventional PI DTC, nonlinear optimal DTC, and adaptive DTC, including less computational burden, less torque and flux ripples, more robustness to parameter uncertainty, and improved transient response under very low speed/load step-changes and speed reversal.
- Published
- 2021
241. Numerical Investigation of Turbulent Junction Flows
- Author
-
Stephen P. Lynch, Zachary D. Robison, John-Paul Mosele, and Andreas Gross
- Subjects
Physics ,Turbulence ,Aerospace Engineering ,Mechanics ,Boundary layer thickness ,Nonlinear Sciences::Chaotic Dynamics ,Physics::Fluid Dynamics ,Particle image velocimetry ,Incompressible flow ,Condensed Matter::Superconductivity ,Horseshoe vortex ,Turbulence kinetic energy ,Reynolds-averaged Navier–Stokes equations ,Computer Science::Databases ,Backflow - Abstract
Turbulent junction flows are known to exhibit a bimodal behavior of the horseshoe vortex that can be described by a random switching between a zero-flow and a backflow mode. The physical mechanism ...
- Published
- 2021
242. Methods of Compacting Electrical Engineering Products from Desorbed Graphite Fiber Composites
- Author
-
Yu. S. Latfulina, M. N. Samodurova, and L. A. Barkov
- Subjects
Condensed Matter::Materials Science ,Materials science ,Mechanics of Materials ,Condensed Matter::Superconductivity ,Metallic materials ,Materials Chemistry ,Metals and Alloys ,Composite material ,Condensed Matter Physics - Abstract
New methods for compacting graphite fiber powder composites developed by the authors are described. These methods help to remove considerable amounts of gases and liquid vapors from powder loaded into the punch-and-die set and from the compact prior to the main compacting operation.
- Published
- 2021
243. Stress Analysis of 13 T Split Superconducting Magnet for Neutron Scattering
- Author
-
Zhu Xulai, Yunfei Tan, Tianjiao Liang, Zhu Sihua, and Yongchao Guo
- Subjects
Materials science ,Physics::Medical Physics ,Stress–strain curve ,Superconducting magnet ,Neutron scattering ,Condensed Matter Physics ,Electronic, Optical and Magnetic Materials ,Magnetic field ,Stress (mechanics) ,Condensed Matter::Superconductivity ,Magnet ,Cylinder stress ,Electrical and Electronic Engineering ,Composite material ,Radial stress - Abstract
The stress and strain analysis is indispensable for the design and development of high field superconducting magnet. In this paper, a stress analysis with elastic and plastic theory for high magnetic field split superconducting magnet was introduced. By the stress analysis theory, the stress of 13 T split superconducting magnet for neutron scattering was simulated and discussed. Based on the analysis results, the structure of coils was modified by three ways including reduce the maximum magnetic field, applied pre-stress and increased thermal stress. After modified, the peak stress is 165 MPa appeared on the third Nb3Sn coils when the magnet is charged to operating current of 114 A. The peak value of radial stress on superconducting coils is 11.4 MPa appeared on the inner Nb3Sn coils reduced from 21.3 MPa. The stress along axis on the coils is less than 80.7 MPa reduced from 90.6 MPa. The hoop stress on the superconducting coils is 154 MPa which effected on the inner side of the third Nb3Sn coils reduced from 171 MPa. The developing risk of 13 T split superconducting magnet for neutron scattering is reduced significantly.
- Published
- 2021
244. Evidence for anisotropic spin-triplet Andreev reflection at the 2D van der Waals ferromagnet/superconductor interface
- Author
-
Ranran Cai, Boning Li, Qing-feng Sun, Shuang Jia, Igor Žutić, Xingwang Xie, Wenyu Xing, Yuan Ji, Yang Ma, Yunyan Yao, Huibin Zhou, Wei Han, Peng Lv, and Chenghao Shen
- Subjects
Magnetoresistance ,Science ,FOS: Physical sciences ,General Physics and Astronomy ,General Biochemistry, Genetics and Molecular Biology ,Article ,Andreev reflection ,Superconducting properties and materials ,Superconductivity (cond-mat.supr-con) ,symbols.namesake ,Surfaces, interfaces and thin films ,Condensed Matter::Superconductivity ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,Symmetry breaking ,Spin (physics) ,Superconductivity ,Physics ,Multidisciplinary ,Condensed matter physics ,Spintronics ,Condensed Matter - Mesoscale and Nanoscale Physics ,Condensed Matter - Superconductivity ,General Chemistry ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,Ferromagnetism ,symbols ,Condensed Matter::Strongly Correlated Electrons ,van der Waals force - Abstract
Fundamental symmetry breaking and relativistic spin–orbit coupling give rise to fascinating phenomena in quantum materials. Of particular interest are the interfaces between ferromagnets and common s-wave superconductors, where the emergent spin-orbit fields support elusive spin-triplet superconductivity, crucial for superconducting spintronics and topologically-protected Majorana bound states. Here, we report the observation of large magnetoresistances at the interface between a quasi-two-dimensional van der Waals ferromagnet Fe0.29TaS2 and a conventional s-wave superconductor NbN, which provides the possible experimental evidence for the spin-triplet Andreev reflection and induced spin-triplet superconductivity at ferromagnet/superconductor interface arising from Rashba spin-orbit coupling. The temperature, voltage, and interfacial barrier dependences of the magnetoresistance further support the induced spin-triplet superconductivity and spin-triplet Andreev reflection. This discovery, together with the impressive advances in two-dimensional van der Waals ferromagnets, opens an important opportunity to design and probe superconducting interfaces with exotic properties., The interfaces between ferromagnets and superconductors receive many attentions due to emergent relativistic spin-orbit coupling. Here, the authors provide possible evidence for spin triplet Andreev reflection at the interface between a van der Waals ferromagnet Fe0.29TaS2 and a s-wave superconductor NbN.
- Published
- 2021
245. Nonmonotonous temperature dependence of Shapiro steps in YBCO grain boundary junctions
- Author
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L. S. Revin, S. A. Pavlov, Dmitriy V. Masterov, Andrey L. Pankratov, and A. E. Parafin
- Subjects
Technology ,Materials science ,Science ,QC1-999 ,characteristic frequency ,General Physics and Astronomy ,Substrate (electronics) ,TP1-1185 ,Signal ,Full Research Paper ,symbols.namesake ,Condensed Matter::Superconductivity ,Nanotechnology ,General Materials Science ,Electrical and Electronic Engineering ,temperature dependence ,Deposition (law) ,shapiro steps ,ybacuo josephson junction ,Condensed matter physics ,Chemical technology ,Physics ,Function (mathematics) ,Nanoscience ,Amplitude ,symbols ,Grain boundary ,Maxima ,Bessel function - Abstract
The amplitudes of the first Shapiro steps for an external signal with frequencies of 72 and 265 GHz are measured as function of the temperature from 20 to 80 K for a 6 μm Josephson grain boundary junction fabricated by YBaCuO film deposition on an yttria-stabilized zirconia bicrystal substrate. Non-monotonic dependences of step heights for different external signal frequencies were found in the limit of a weak driving signal, with the maxima occurring at different points as function of the temperature. The step heights are in agreement with the calculations based on the resistively–capacitively shunted junction model and Bessel theory. The emergence of the receiving optima is explained by the mutual influence of the varying critical current and the characteristic frequency.
- Published
- 2021
246. Mass of Abrikosov vortex in high-temperature superconductor YBa $$_2$$ 2 Cu $$_3$$ 3 O $$_{7-\delta }$$ 7 - δ
- Author
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Roman Tesař, Michal Šindler, Christelle Kadlec, Pavel Lipavský, Ladislav Skrbek, and Jan Koláček
- Subjects
Condensed Matter::Superconductivity ,Science ,Medicine - Abstract
For more than four decades, mass of Abrikosov vortices defied experimental observations. We demonstrate a method of its detection in high-temperature superconductors. Similarly to electrons, fluxons circulate in the direction given by the magnetic field, causing circular dichroism. We report the magneto-transmittance of a nearly optimally doped thin YBa $$_2$$ 2 Cu $$_3$$ 3 O $$_{7-\delta }$$ 7 - δ film, measured using circularly polarized submillimeter waves. The circular dichroism emerges in the superconducting state and increases with dropping temperature. Our results confirm the dominant role of quasiparticle states in the vortex core and yield the diagonal fluxon mass of $$2.2 \times 10^8$$ 2.2 × 10 8 electron masses per centimeter at 45 K and zero-frequency limit, and even larger off-diagonal mass of $$4.9 \times 10^8 m_e$$ 4.9 × 10 8 m e /cm.
- Published
- 2021
247. Epitaxial Heterostructure of a Cuprate Superconductor and Praseodymium Nickelate
- Author
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Petrzhik, A.M., Shadrin, A.V., Kislinskii, Yu.V., Constantinian, K.Y., Ovsyannikov, G.A., Cristiani, G., and Logvenov, G.
- Subjects
Condensed Matter::Materials Science ,Condensed Matter::Superconductivity ,Condensed Matter::Strongly Correlated Electrons ,Surfaces, Coatings and Films - Abstract
Heterostructures with epitaxial interfaces of transition metal oxides with superconducting properties and materials with strain-controlled characteristics, in particular with nickelates, attract an increased interest due to opportunities for development of electronic devices with spin polarized electron transport.
- Published
- 2021
248. Applied Superconductivity and Electromagnetic Devices - Large-Scale Applications and Availability
- Author
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Teng Liu, Xinsheng Yang, Longxiang Liu, Qian Zhou, Junjie Du, Zhuyong Li, Bingfu Gu, Guoshu Zhang, Sansheng Wang, Team Asemd, Shan Jiang, Jinggang Qin, Liangting Sun, Yong Zhao, Zhijian Jin, Chao Zhou, Jie Sheng, Huan Jin, Enming Mei, and Wei Wu
- Subjects
Superconductivity ,Scale (ratio) ,Condensed Matter::Superconductivity ,Electromagnetic devices ,Superconducting magnet ,Electrical and Electronic Engineering ,Condensed Matter Physics ,Engineering physics ,Electronic, Optical and Magnetic Materials ,Magnetic field - Abstract
Practical superconducting materials and technologies have been enabled with availability for large scale devices and applications. Various large scale and strong magnetic field applications of superconductors have been developed, and a series of those applications are explored with technical details mainly including i) applied superconducting materials and their characteristics; ii) superconducting magnets and their techniques; iii) large and advanced electromagnetic devices and applications. The applied superconductivity, application technology, and availability are especially focused and verified with the trend of large scale applications’ development prospection.
- Published
- 2021
249. Understanding the creep behavior of shale via nano-DMA method
- Author
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Kouqi Liu, Xiaomeng Xu, Lianbo Zeng, Mehdi Ostadhassan, and Zhijun Jin
- Subjects
Materials science ,Modulus ,Nanoindentation ,Shale ,Instability ,TK1-9971 ,Physics::Geophysics ,General Energy ,Creep ,Condensed Matter::Superconductivity ,Phase (matter) ,Nano-DMA ,Electrical engineering. Electronics. Nuclear engineering ,Composite material ,Displacement (fluid) ,Quartz ,Oil shale ,Creep behavior ,Contact creep modulus - Abstract
Understanding the creep behavior of shale is essential to precisely predict borehole instability issues and model fracturing of unconventional shale reservoirs. In this study, the creep behavior of shale in micron scale is investigated by integrating the nano-dynamic mechanical analysis (nano-DMA) grid nanoindentation (15 × 15 indents) and data clustering techniques. The results showed that the creep displacement, the creep rate, and hardness, both can be related through a logarithmic function with creep time. Furthermore, contact creep modulus increased as the hardness or Young’s modulus increased. The clustering analysis revealed that three separate phases are present in the samples where Phase 1(clay/organic matter) has the smallest contact creep modulus and Phase 3 (quartz) the largest. While creep is in progress, the creep displacement, hardness and contact creep modulus of all three phases obey the logarithmic function. Under the same creep time, reduction in the contact creep modulus of Phase 3 appears to be faster than Phase 1 while the creep rate of Phase 3 is much less than Phase 1. Ultimately, contact creep modulus is better correlated with hardness than Young’s modulus.
- Published
- 2021
250. Improved Superconducting Properties of NaCl Doped MgB2
- Author
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Yong Zhao, Yu Lin, Yongliang Chen, Zhou Yu, Liang Zheng, Yutong Liu, Yong Zhang, Dajin Zhou, C.H. Cheng, and Xinsheng Yang
- Subjects
Superconductivity ,Materials science ,Flux pinning ,Condensed matter physics ,Doping ,Condensed Matter Physics ,Magnetic flux ,Grain size ,Electronic, Optical and Magnetic Materials ,Magnetization ,Condensed Matter::Superconductivity ,Grain boundary ,Electrical and Electronic Engineering ,Pinning force - Abstract
MgB2 superconducting materials have important application potential in the 20K temperature region, which is a significant advantage compared with other low-temperature superconductors (such as Nb-Ti and Nb3Sn). However, there is a big gap between its superconducting current-carrying capacity and Ni-Ti and Nb3Sn, which is due to the weak magnetic flux pinning force and the poor connection between the MgB2 grains. Chemical doping is a simple and effective method to improve the performance of MgB2. This paper studies the effect of NaCl doping on the performance of MgB2. It is found that NaCl doping has a positive effect on improving the interconnection of MgB2 grains and refining MgB2 grains, and is a potentially effective method to improve the superconducting properties of MgB2. In addition, all of the samples in this study showed surface pinning characteristics, but the smaller the MgB2 grain size, the better the match with the surface pinning characteristics described by Kramer's theory.
- Published
- 2021
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