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Topological insulating phase in commonly used semiconductors

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National Science Review 2014年第1期1卷 34-35页

作者： kai chang SKLSM Institute of Semiconductors Chinese Academy of Sciences

Interface polarization between commonly used semiconductors provides a possible method to drive commonly used semiconductors into their topological insulating *** insulators(TIs)have attracted interest over recent years,with properties such as an insulating bulk region,robust metallic edges or surface modes and topological *** have potential applications ranging from spintronic devices to quantum computation[1–8].Despite recent progress,

关键词： Ga As Topological insulating phase in commonly used semiconductors

Reverse Engineering of Machine-tool Settings with Modified Roll for Spiral Bevel Pinions

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Chinese Journal of Mechanical Engineering 2013年第3期26卷 573-584页

作者： LIU Guanglei chang kai LIU Zeliang School of Mechatronics Northwestern Polytechnical University

Although a great deal of research has been dedicated to the synthesis of spiral bevel gears, little related to reverse engineering can be found. An approach is proposed to reverse the machine-tool settings of the pinion of a spiral bevel gear drive on the basis of the blank and tooth surface data obtained by a coordinate measuring machine(CMM). Real tooth contact analysis(RTCA) is performed to preliminary ascertain the contact pattern, the motion curve, as well as the position of the mean contact point. And then the tangent to the contact path and the motion curve are interpolated in the sense of the least square method to extract the initial values of the bias angle and the higher order coefficients(HOC) in modified roll motion. A trial tooth surface is generated by machine-tool settings derived from the local synthesis relating to the initial meshing performances and modified roll motion. An optimization objective is formed which equals the tooth surface deviation between the real tooth surface and the trial tooth surface. The design variables are the parameters describing the meshing performances at the mean contact point in addition to the HOC. When the objective is optimized within an arbitrarily given convergence tolerance, the machine-tool settings together with the HOC are obtained. The proposed approach is verified by a spiral bevel pinion used in the accessory gear box of an aviation engine. The trial tooth surfaces approach to the real tooth surface on the whole in the example. The results show that the convergent tooth surface deviation for the concave side on the average is less than 0.5 μm, and is less than 1.3 μm for the convex side. The biggest tooth surface deviation is 6.7 μm which is located at the corner of the grid on the convex side. Those nodes with relative bigger tooth surface deviations are all located at the boundary of the grid. An approach is proposed to figure out the machine-tool settings of a spiral bevel pinion by way of reverse engi

关键词： spiral bevel gears pinion manufacture parameters modified roll real tooth contact analysis reverse engineering

Spin-orbit interaction induced Casimir-Lifshitz torque between two-dimensional electron gases

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Science China(Physics,Mechanics & Astronomy) 2024年第8期67卷 134-142页

作者： Jia-Nan Rong Liang Chen kai chang State Key Laboratory of Superlattices and Microstructures Institute of SemiconductorsChinese Academy of SciencesBeijing 100083China School of Mathematics and Physics North China Electric Power UniversityBeijing 102206China School of Physics Zhejiang UniversityHangzhou 310027China College of Materials Science and Opto-electronic Technology University of Chinese Academy of SciencesBeijing 100049China

We investigate theoretically the Casimir interaction between two parallel two-dimensional electron gases(2DEGs)with Rashba and Dresselhaus spin-orbit interactions(SOIs),based on the quantum field *** derive an analytical expression for the polarization tensor and obtain the solution to the motion equation of the electromagnetic(EM)*** calculate the CasimirLifshitz torque(CLT)between two parallel 2DEGs with Rashba and Dresselhaus SOIs,which can be tuned by changing the relative strength between two *** anisotropic Casimir energy between 2DEGs caused by the interplay between the SOIs of 2DEGs offers a new origin of CLT and a new type of optoelectronic device.

关键词： Casimir torque two-dimensional electron gas spin-orbit interaction

Effect of Electric Field on the Electron-Surface Optical Phonon Scattering Rates in Quantum Wires

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Chinese Physics Letters 1996年第4期13卷 297-300页

作者： chang kai WANG Ruo-zhen MA Ben-kun Department of Physics Beijing Normal UniversityBeijing 100875

By using the variational method and the dielectric continuum model,we investigate the effect of electric Held on the intrasubband scattering rates of electron-surface optical *** results show that the scattering rates tend to increase with the electric field *** scattering rates become significant for wide quantum well wire and sufficiently high fields.

关键词： strength. Electron variational

Exciton Vortices in Two-Dimensional Hybrid Perovskite Monolayers

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Chinese Physics Letters 2020年第11期37卷 65-69页

作者： Yingda Chen Dong Zhang kai chang State Key Laboratory for Superlattices and Microstructures Institute of SemiconductorsChinese Academy of SciencesBeijing 100083China CAS Center for Excellence in Topological Quantum Computation University of Chinese Academy of SciencesBeijing 100190China Beijing Academy of Quantum Information Sciences Beijing 100193China

We study theoretically the exciton Bose–Einstein condensation and exciton vortices in a two-dimensional(2 D)perovskite(PEA)2 Pb I4 *** the first-principles calculations and the Keldysh model,the exciton binding energy of in a(PEA)2 Pb I4 monolayer can approach hundreds of me V,which make it possible to observe the excitonic effect at room *** to the large exciton binding energy,and hence the high density of excitons,we find that the critical temperature of the exciton condensation could approach the liquid nitrogen *** the presence of perpendicular electric fields,the dipole-dipole interaction between excitons is found to drive the condensed excitons confined in(PEA)2 Pb I4 monolayer flakes into patterned vortices,as the evolution time of vortex patterns is comparable to the exciton lifetime.

关键词： temperature. monolayer dipole

Even-odd-dependent optical transitions of zigzag monolayer black phosphorus nanoribbons

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Science China(Physics,Mechanics & Astronomy) 2021年第1期64卷 91-101页

作者： Pu Liu XianZhe Zhu XiaoYing Zhou GuangHui Zhou kai chang Department of Physics Key Laboratory for Low-Dimensional Structures and Quantum Manipulation(Ministry of Education)Synergetic Innovation Center for Quantum Effects and Applications of HunanHunan Normal UniversityChangsha410081China SKLSM Institute of SemiconductorsChinese Academy of SciencesBeijing100083China

We analytically study the electronic structure and optical properties of zigzag-edged phosphorene nanoribbons(ZPNRs) using the tight-binding Hamiltonian and Kubo formula. By directly solving the discrete Schrodinger equation, we obtain the energy spectra and wavefunctions for N-ZPNR(where N is the number of transverse zigzag atomic chains) and classify the eigenstates according to the lattice symmetry. Then, we obtain the optical transition selection rule of ZPNRs on the basis of symmetry analysis and analytical expressions of optical transition matrix elements. Under incident light that is linearly polarized along the ribbon, we determine that the optical transition selection rule for N-ZPNR with even-or odd-N is qualitatively different. Specifically, for even-N ZPNRs, the inter-(intra-) band selection rule is ?n =odd(even) because the parity of the wavefunction corresponding to the n-th subband in the conduction(valence) band is(-1)~n[(-1)~((n+1))] owing to the presence of C(2x) symmetry. However, the optical transitions between any subbands are possible owing to the absence of C(2x) symmetry. Our results provide a further understanding on the electronic states and optical properties of ZPNRs, which are useful for explaining the optical experiment data on ZPNR samples.

关键词： zigzag-edged phosphorene nanoribbons band structure light absorption selection rules

Purification and Crystallization of Flammulin,a Basic Protein with Anti-tumor Activities from Flammulina Velutipes

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Chinese Chemical Letters 2003年第7期14卷 713-716页

作者： kai Song ZHOU Jun Feng PENG Ning chang Han Xing ZHANG Feng GONG chang kai ZHANG National Key Lab of Microbial Technology Shandong UniversityJinan 250100

Flammulin, an anti-tumor protein, was purified from the aqueous extract of basidiomes of Flammulina Velutipes to electrophoretic homogeneity and crystallized by microdialysis against a polyethylene glycol- sodium phosphate buffer. The purified product was found to have marked anti-tumor effects and be able to affect the tumor cells directly.

关键词： Flammulin purification crystallization.

Chiral Anomaly-Enhanced Casimir Interaction between Weyl Semimetals

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Chinese Physics Letters 2021年第8期38卷 57-61页

作者： Jia-Nan Rong Liang Chen kai chang SKLSM Institute of SemiconductorsChinese Academy of SciencesBeijing 100083China School of Mathematics and Physics North China Electric Power UniversityBeijing 102206China CAS Center for Excellence in Topological Quantum Computation University of Chinese Academy of SciencesBeijing 100190China

We theoretically study the Casimir interaction between Weyl *** the distance a between semiinfinite Weyl semimetals is in the micrometer regime,the Casimir attraction can be enhanced by the chiral *** Casimir attraction depends sensitively on the relative orientations between the separations(b1,b2)of Weyl nodes in the Brillouin zone and show anisotropic behavior for the relative orientation of these separations(b1,b2)when they orient parallel to the *** anisotropy is quite larger than that in conventional birefringent *** Casimir force can be repulsive in the micrometer regime if the Weyl semimetal slabs are sufficiently thin and the direction of Weyl nodes separations(b1,b2)is perpendicular to the *** Casimir attraction between Weyl semimetal slabs decays slower than 1/a4 when the Weyl nodes separations b1 and b2 are both parallel to the interface.

关键词： materials separation attraction

Numerical analysis of pile–slope stability and the soil arching around two adjacent piles

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Journal of Mountain Science 2022年第11期19卷 3270-3285页

作者： Chien-Yuan CHEN Chun-kai chang Yu-Shan LIN Department of Civil and Water Resources Engineering National Chiayi UniversityChiayi City 60004Chinese Taipei

Seismic pile–slope stability analysis and the formation mechanism of soil arching have not been well studied. This study used a threedimensional(3D) finite difference to determine soil and pile parameter changes in the static and seismic stability of the pile–slope caused by the interaction between stabilizing piles. Pile–slope stability analysis was performed to determine the optimal design of piles along a slope and the corresponding failure mode involving the formation of soil arching around two adjacent piles. The Factor of Safety(FS) of the slope was evaluated using the shear strength reduction method for static and seismic analyses. The results of the analysis show that suitable pile spacing(S) and a suitable pile diameter(D) in the middle of a slope result in the maximum FS for the pile–slope system and the formation of soil arching around two adjacent piles. FS of the pile–slope increased negligibly in the seismic analysis of piles located at the slope crest and toe. An optimized pile diameter and installation location afforded the maximum FS for the slope that corresponded to a specified slope failure mode for different pile locations. A pile spacing S ≤ 2.5D for piles installed in the middle of the slope is suggested for increasing the static and seismic pile–slope stability.

关键词： Numerical modeling Slope stability Stabilizing pile Arching effect Seismic analysis Failure mode