bluuebunny/crossref_metadata_2025 huggingface dataset:
The traffic flow of two-lane system with vehicle mixing
Authors: Zheng Rong-Sen  , Tan Hui-Li  , Kong Ling-Jiang  , Liu Mu-Ren  ,   (1)广西师范大学物理与信息工程学院，桂林  541004; (2)玉林师范学院物理与信息科学系，玉林  537000
Published: December 2020

A cellular automaton model for two-lane traffic with vehicle mixing basing on the Nagel-Schreckenberg (NaSch) model is proposed. With different parameters, we simulated the traffic flow of the two-lane system when the vehicle densities of lanes are equal or different respectively. The fundamental diagrams of the traffic flow are given. According to the analysis, the traffic state could be divided into three regions.The nonsymmetry of car density on two lanes has important influence on the traffic flow.
Optical absorption, Raman spectra and TEM study of Ag nanoparticles formed by ion implantation into a-SiO2
Authors: Liu Xiang-Fei  , Jiang Chang-Zhong  , Ren Feng  , Fu Qiang  ,   (1)武汉大学物理科学与技术学院，武汉  430072; (2)武汉大学物理科学与技术学院，武汉  430072;武汉大学电子显微镜中心，武汉  430072
Published: December 2020

Silver nanoparticles are formed by ion implantation into amorphous silica matrix at 200 keV at room temperature with doses of 1×1016, 5×1016 and 1×1017 cm-2. The sizes，distributions and shapes of the silver nanoparticles in the samples were obtained by transmission electron microscopy, which is greatly influenced by the dose. The effect of size，distribution and shape of the silver nanoparticles to the optical resonant absorption peak is been discussed. Optical absorption spectra of samples implanted with 5×1016 and 1×1017Ag+ cm-2 showed absorption peaks shifted to red, the intensity of absorption peak increased and shoulder peaks appeared, compared with the absorption spectra of the sample implanted with 1×1016Ag cm-2. The red-shift of absorption peaks and the appearance of shoulder peaks are due to the increasing volume factor and the multipolar plasmon induced by the interaction of nanoparticles, respectively. Raman scattering spectroscopy indicates that there are many defects in the high-dose implanted samples. Nanocavities in the large Ag nanoparticles are discovered in the sample with the dose of 1×1017 cm-2 possibly due to the aggregation of implant-induced silicon and oxygen atoms in Ag nanoparticles.
EMS investigation of inner valance orbital 1a" for butanone
Authors: Li Gui-Qin  , Deng Jing-Kang  , Li Bin  , Ren Xue-Guang  , Ning Chuan-Gang  , Zhang Shu-Feng  , Su Guo-Lin  ,   清华大学物理系，北京  100084
Published: December 2020

The binding energy and the spherically averaged momentum distributions of orbital 1a″for butanone have been investigated by high resolution electron momentum spectroscopy (ΔE=1.15eV, Δp=0.1a.u.). The impact energy was 1200eV plus binding energy (i.e. 1206—1242eV) and symmetric non-coplanar kinematics was employed. The experimental binding energy spectra have been compared with published photoelectron spectra. The momentum profile of 1a″ orbital has been compared on a quantitative basis with theoretical calculations using Hartree-Fock method and Density Functional Theory. The position density and momentum density for 1a″ orbital are presented.
Ultrafast electronic dymamics during femtosecond laser-induced damage in omnidirectional reflector
Authors: Sun Hai-Yi  , Jia Tian-Qing  , Li Xiao-Xi  , Xu Shi-Zhen  , Feng Dong-Hai  , Li Cheng-Bin  , Wang Xiao-Feng  , Xu Zhi-Zhan  ,   中国科学院上海光学精密机械研究所强场激光物理国家重点实验室，上海  201800
Published: December 2020

The use of optical frequency domain phase conjugation (FDPC) to suppress pulse impairments due to cross-phase modulation (XPM) in optical fiber systems is propo sed. Evolution of Gaussian pulses in the system using midway FDPC is analyzed thoretically and simulated numerically. It is found that pulse waveform impairmen ts induced by XPM can be suppressed effectively by FDPC. The impairments due to group-velocity dispersion and self-phase modulation can be suppressed simultaneously. Suitable initial time delay and pulse chirp of pulses can improve the suppression and compensation for the distortion.
Magnetism and transport properties of Heusler alloy Co2TiSn
Authors: Zhang Wei  , Qian Zheng-Nan  , Sui Yu  , Liu Yu-Qiang  , Su Wen-Hui  , Zhang Ming  , Liu Zhu-Hong  , Liu Guo-Dong  , Wu Guang-Heng  ,   (1)哈尔滨工业大学凝聚态科学与技术中心,哈尔滨  150001; (2)中国科学院物理研究所磁学国家重点实验室,北京  100080
Published: December 2020

Magnetism and transport properties of the Heusler alloy Co2TiSn are s tudied. The results show this alloy exhibits ferrimagnetic structure at low fiel d. Both resistance and Hall resistivity show anomalies below 8K. An analysis is given for the microscopic scattering mechanisms of electric transport. The origi n of anomalous Hall effect is discussed.
Characterization of transitions in MnFeP0.45As0.55 compound
Authors: Zhu Zhi-Yong  , Wang Wen-Quan  , Miao Yuan-Hua  , Wang Yan-Song  , Chen Li-Jie  , Dai Xue-Fang  , Liu Guo-Dong  , Chen Jing-Lan  , Wu Guang-Heng  ,   (1)吉林大学物理学院,长春  130023; (2)中国科学院物理研究所北京凝聚态物理国家实验室,北京  100080
Published: December 2020

The resistance, magnetization and strain measurements have been carried out on MnFeP0.45As0.55 compound. We found that, at variance with what is commonly believed, the critical temperature points for the first order t ransition, paramagnetism-ferromagnetism transition, and lattice anomaly are not identical. The first order transition goes on in a quite wide temperature range with a thermal hysteresis of about 10K. In the duration of the first order trans ition, the paramagnetism-ferromagnetism transition is observed, which indicates that they are not related to the lattice anomaly. Thus, we attribute it to the continuous change of the lattice parameters due to the structure transition bas ed on our observation and Zach et al.'s work. On the other hand, the lattice ano maly occurs at lower temperature than that of the first order structural and mag netic transitions. We conclude that it is a magnetostrictive behavior associate d with the magnetoelastic coupling below the Curie temperature.
Self-trapping and its periodic modulation of Bose-Einstein condensates in double-well trap
Authors: Wang Guan-Fang  , Fu Li-Bin  , Zhao Hong  , Liu Jie  ,   (1)北京应用物理与计算数学研究所,北京  100088; (2)兰州大学物理科学与技术学院理论物理研究所,兰州  730000; (3)兰州大学物理科学与技术学院理论物理研究所,兰州  730000;中国工程物理研究院北京研究生部，北京  100088
Published: December 2020

Self-trapping of Bose-Einstein condensates (BEC) in double-well trap is investigated. Two kinds of self-trapping are discussed through phase space analysis in the mean-field approximation: 1) The number of atoms oscillates near an equilibrium point in the phase space, while relative phase increases monotonously with time (running-phase); 2) Both the number of particles and the relative phase oscillate near an equilibrium point in the phase space. In particular, we investigate how an external periodic filed influence the self-trapping. It is found that the external periodic field may dramatically modulate the critical points at which the transition to self-trapping occurs. With this, we can observe self-trapping phenomenon in a dilute Bose-Einstein condensate with a very weak interaction as well. Finally, the effect of many-body quantum fluctuation on self-trapping is also studied. We also discuss how to observe the self-trapping phenomenon with present experimental techniques.
Using quantum tunneling method Hawking radiation of a static black hole horizon with a mass-quadrupole moment is studied
Authors: Han Yi-Wen  ,   达县师范高等专科学校物理系，达州  635000
Published: December 2020

This paper presents a straightforward derivation of Hawking radiation from a static black hole possessing mass-quadrupole moment as a tunneling process,and the radiation spectrum is obtained.Because the derivation assumes conservation laws,the exact spectrum is not precisely thermal. This result supports the viewpoint that it is possible for the radiation via tunneling to have information-carrying capabilities.
A new method of global prediction for chaotic time series based on continued fractions
Authors: Zhang Sen  , Xiao Xian-Ci  ,   (1)电子科技大学电子工程学院,成都  610054; (2)电子科技大学电子工程学院,成都  610054;宜宾学院数学系,四川  644007
Published: December 2020

A non-linear predictable global model for chaotic time series is built based on continued fractions after developing the method of polynomial approximants in theory. We can analyze the characteristics and realize the prediction by substituting the model for the equation of chaotic time series. The results of theoretical analysis and computer simulation have proved this method to be practically feasible for predicting a chaotic series accurately and give its explicit expression.
The magnetic fine structure calculation of helium 10G—10M Rydberg states
Authors: Zhu Yun-Xia  , He Li-Ming  , Cao Wei  , Ge Zi-Ming  ,   华东理工大学物理系，上海  200237
Published: December 2020

With self-consistent iterative method for solving the Hartree equation, precise numerical wavefunctions of helium 1snl configuration are generated to build up the LS term wavefunctions as basis sets. The magnetic fine structure of helium 10G—10M Rydberg states is calculated with the linear variation method, including both the exchange and magnetic interaction under the Breit-Bethe approximation. The calculated results agree well with the existing experiment data. Some ideas and discussions for further improvement are given.
Identifying single molecule based on the photon statistics
Authors: Peng Shuang-Yan  , Huang Tao  , Wang Xiao-Bo  , Shao Jun-Hu  , Xiao Liao-Tuan  , Jia Suo-Tang  ,   (1)量子光学与光量子器件国家重点实验室，山西大学物理电子工程学院，太原  030006; (2)量子光学与光量子器件国家重点实验室，山西大学物理电子工程学院，太原  030006;贵州毕节学院物理系，毕节  551700
Published: December 2020

We theoretically study the photon counting statistics characterizations of the real single molecular photon source with a Poisson statistics background and that of an ideal double molecular system based on the standard HBT detection. Mandel parameter Q of each source with the same mean photons n—was analyzed. We have obtained an efficient method to identify single molecule by the two-photon statistics probability P(2), which shows the relation P(2)2. Additionally, we studied the effect of single-to-background ratio of the single molecular photon source on the criterion.
Self-compression of femtosecond laser pulses in normally dispersive solid material
Authors: Chen Xiao-Wei  , Zhu Yi  , Liu Jun  , Leng Yu-Xin  , Ge Xiao-Chun  , Li Ru-Xin  , Xu Zhi-Zhan  ,   (1)中国科学院上海光学精密机械研究所，强场激光物理国家重点实验室，上海  201800; (2)中国科学院上海光学精密机械研究所，强场激光物理国家重点实验室，上海  201801; (3)中国科学院上海光学精密机械研究所，强场激光物理国家重点实验室，上海  201802; (4)中国科学院上海光学精密机械研究所，强场激光物理国家重点实验室，上海  201803; (5)中国科学院上海光学精密机械研究所，强场激光物理国家重点实验室，上海  201804; (6)中国科学院上海光学精密机械研究所，强场激光物理国家重点实验室，上海  201805; (7)中国科学院上海光学精密
Published: December 2020

We have experimentally demonstrated the self-compression of gegawatt high power femtosecond laser pulses in normally dispersive solid bulk media. It was proved that high-power femtosecond laser pulses can be compressed during the self-focusing propagation in the transparent nonlinear medium. The self-compression behavior was investigated in detail under a variety of experimental conditions, and the temporal and spectral characteristics of resulted pulses are found to be significantly affected by the input pulse intensity, with higher intensity corresponding to shorter compressed pulse. However, the output pulse is split into two peaks when the input intensity is high enough to lead to supercontinuum and conical emission. By the propagation in a piece of BK7 glass, a self-compression from 50fs to 20fs is achieved, with a compression factor of about 2.5. Moreover, we find that pulse self-compression can be achieved with a divergent input laser beam into the glass.
Baman scattering intensity of single-wall carbon nanotubes
Authors: Wu Yan-Zhao  , Yu Ping  , Wang Yu-Fang  , Jin Qing-Hua  , Ding Da-Tong  , Lan Guo-Xiang  ,   南开大学物理科学学院,天津  300071
Published: December 2020

A study based on non-resonant bond polrizability model is maded on the Raman scattering intensity of single-wall carbon nanotube.The structure of nanotube,polarization of light and sample orientation dependence of the Raman intensity was discussed by varying the direction of the nanotube axis.It is found that the polarization of light have large effect on the Raman spectra,while the chirality of the carbon nanotube has little effect.The chirality and diameter dependence of the Raman intensity were calculated using the theory of randomly oriented particles.
Thermal stability of magnetic tunnel junctions investigated by x-ray photoelectron spectroscopy
Authors: Feng Yu-Qing  , Zhao Kun  , Zhu Tao  , Zhan Wen-Shan  ,   (1)聊城大学物理与信息工程学院磁电子实验室，聊城  252059; (2)中国科学院物理研究所磁学国家重点实验室，北京  100080
Published: December 2020

We have studied the thermal stability of magnetic tunnel junctions with and without nano-oxide layer (NOL) using x-ray hpotoelectron spectroscopy (XPS). The con centration and chemical states of elements,in particular Mn,have been obtained b y angel-resolved XPS and peak decomposition technique.It is confirmed that Mn in the antiferromagnetic layer can diffuse into the pinned ferromagnetic layer and the insulating barrier layer when a magnetic tunnel junction without NOL is ann ealed at high temperature.However,the interdiffusion of Mn during the annealing process is suppressed by inserting a NOL between the antiferromagnetic and pinne d ferromagnetic layer,and then the thermal stability is improved.
Effect of Ag on the structure and magnetic properties of CoPt/Ag nanocomposite films
Authors: Xue Shuang-Xi  , Wang Hao  , Yang Fu-Jun  , Wang Jun-An  , Cao Xin  , Wang Han-Bin  , Gao Yun  , Huang Zhong-Bing  , Feng Jie  , Cheung W. Y.  , Wong S. P.  , Zhao Zi-Qiang  ,   (1)北京大学重离子物理教育部重点实验室，北京  100871; (2)湖北大学物理学与电子技术学院暨纳米技术研究中心，武汉  430062; (3)香港中文大学电子工程系，香港
Published: December 2020

CoPt/Ag nanocomposite films were prepared by magnetron sputtering. The dependenc e of texture and magnetic properties on film thickness, bilayer thickness, Ag at omic fraction and annealing conditions is investigated. Films with thickness bel ow 20 nm are apt to form (001) orientation. The existence of the Ag in the film plays a dominant role in inducing the (001) texture of the film besiles suppress ing the growth of the CoPt grains during annealing. The Co40Pt43 Ag17 film after annealing at 600℃ exhibits a large perpendicul ar coercivity of HC=5.6×105 A/m, a large saturation magne tization of MS=0.65T and a squareness of s=0.95 of the hysteresis loo p.
Thermodynamic effects on the sintered Nd-Fe-B magnets
Authors: Li Zheng  , He Ye-Qing  , Hu Bo-Ping  , Wang Zhen-Xi  ,   (1)北京中科三环高技术股份有限公司，北京  100080; (2)北京中科三环高技术股份有限公司，北京  100080;中国科学院物理研究所，北京凝聚态物理国家实验室，北京  100080;中国科学院研究生院，北京  100080
Published: December 2020

In the sintered Nd-Fe-B magnets, the forming of various phases, substitution and preference of additive atoms, microstructure and properties, and, most of proce ssing have a close relationship to the thermodynamics. The Al, Cu, Ga, Sn, Zn ha ve positive heat of mixing with the B, the solubility of them in the main phase is small, they react with Nd in the grain boundary and modifying the microstruct ure of the magnets. The Zr, Ti, Nb, W, Mo, V, Cr have large positive heat of mix ing with Nd while have large negative heat of mixing with the B, they can modify the microstructure as well as dilute the magnets. The effects of the common add itional elements on the microstructure, properties and the processes of Nd-Fe-B magnets are discussed in this work by referring the heat of mixing and the binar y diagrams.
Residual stress in the GaN epitaxial film prepared by in situ SiNx deposition
Authors: Qin Qi  , Yu Nai-Sen  , Guo Li-Wei  , Wang Yang  , Zhu Xue-Liang  , Chen Hong  , Zhou Jun-Ming  ,   中国科学院物理研究所，表面物理国家重点实验室，北京  100080
Published: December 2020

GaN epitaxial films were grown on c-face sapphire substrates by metalorganic chemical vapor deposition (MOCVD) with an in situ SiNx deposition insert ed into the normal growth process. The in situ SiNx deposition makes a nanomask on GaN, followed by the epitaxial lateral overgrowth on it. Raman spe ctra and photoluminescence are used to study the stress state of the resulting G aN film. The formation of SiNx nanomask leads to a 2D-3D growth mode transition, which ends in the total coalesce of the GaN film. The distribution o f stress state in this kind of GaN film is more uniform than that of films grown by the conventional epitaxial lateral overgrowth. The data about the relaxation of the stress deduced by the Raman spectra match well with those obtained by ph otoluminescence. These data also show that the more residual stress in the GaN f ilm grown on the SiNx nanomask is relaxed when the time of in situ Si Nx deposition is increased. This is because with the increasing time of in situ SiNx deposition, the wing area of epitaxial lateral overgr owth becomes larger, which will reduce the stress in the GaN thin film grown on it.
Vacuum ultraviolet spectroscopic properties and 4f5d state of Pr3+doped YAG
Authors: Meng Chun-Xia  , Huang Shi-Hua  , You Fang-Tian  , Chang Jian-Jun  , Peng Hong-Shang  , Tao Ye  , Zhang Guo-Bin  ,   (1)北京交通大学光电子技术研究所, 北京  100044; (2)中国科学技术大学国家同步辐射实验室, 合肥  230026; (3)中国科学院高能物理研究所同步辐射实验室,北京  100039
Published: December 2020

Yttrium aluminum garnet (YAG): Pr3+ is synthesized by codeposition me thod. Vacuum ultraviolet (VUV) excitation and emission spectra of YAG: Pr3+ at different temperatures are measured using synchrotron radiation as an excitation source. We analyze the transition process after excitation to 4f5d en ergy band and estimate the Huang-Rhys factor S and phonon energy ηω of YAG: Pr 3+ by multi-phonon relaxation. Emission of self-trapped exciton (STE) and 3P0→3H4,5,6 emission transferr ed from the STE energy appear when YAG: Pr3+is excited by 170nm, whic h is a different transition process from those excited by 240nm and 289nm.
Synthesis and thermoelectric properties of dual-atom filled p-type CamCenFexCo4－xSb12 compounds
Authors: Li Han  , Tang Xin-Feng  , Liu Tao-Xiang  , Song Chen  , Zhang Qing-Jie  ,   武汉理工大学材料复合新技术国家重点实验室，武汉  430070
Published: December 2020

The single-phase dual-atom filled p-type CamCenFexCo4-xSb12 compounds were synthesized by melting reactio n method. Effects of Ca and Ce filling fraction on the thermoelectric properties of the p-type CamCenFexCo4-xSb 12 were investigated. Our results indicate that with the same filling frac tion, carrier concentration and electrical conductivity of p-type Cam CenFexCo4-xSb12 intervene between t hat of single atom filled compounds CamFexCo4-x Sb12 and CenFexCo4-xSb12, and decreased with increasing Ca and Ce, especially Ce, filling fraction. With the same filling fraction, the lattice thermal conductivity of CamCenFexCo4-xSb12 is smaller than that of CamFexCo4-xSb12 and CenF exCo4-xSb12. Furthermore, when the total fillin g fraction (m+n) is about 0.3 and the filling fractions of Ca and Ce are approxi mately equal, the lattice thermal conductivity is the smallest. The greatest ZT value of 1.17 was obtained at 750K for p-type Ca0.18Ce0.12 Fe1.45Co2.55Sb12.21.
d'Alembert-Lagrange principle on Riemann-Cartan space
Authors: Wang Yong  , Guo Yong-Xin  ,   (1)广东医学院基础学院，东莞  523808; (2)辽宁大学物理系，沈阳  110036
Published: December 2020

The nonholonomic mapping put forward by Kleinert is generalized to a first-order linear mapping. By means of this method, Riemann-Cartan space is embedded into Euclidean space. Based on this construction, the d'Alembert-Lagrange principle of nonholonomic constrained systems in Euclidean space is reduced to an “unconstrained” representation on Riemann-Cartan space.
Unified symmetry of the holonomic system in terms of quasi-coordinates
Authors: Xu Xue-Jun  , Mei Feng-Xiang  ,   (1)北京理工大学力学系，北京  100081; (2)北京理工大学力学系，北京  100081;浙江师范大学物理系，金华  321004
Published: December 2020

This paper discusses the unified symmetry of a holonomic mechanical system in terms of quasi-coordinates under special infinitesimal transformations in which time is not varied. The differential equations of motion of the system are given. The definition and the criterion of the unified symmetry for the system are presented. A new conserved quantity, besides the Noether conserved quantity and the Hojman conserved quantity, is deduced from the unified symmetry. An example is iven to illustrate the application of the results.
New soliton structures in the (2+1)-dimensional nonlinear KdV equations
Authors: He Bao-Gang  , Xu Chang-Zhi  , Zhang Jie-Fang  ,   (1)浙江师范大学非线性物理研究所，金华  321004; (2)浙江师范大学非线性物理研究所，金华  321004;金华教育学院物理系，金华  321000
Published: December 2020

A new variable separation approach for the (2+1)-dimensional nonlinear KdV equations is obtained by using variable separation technique and selecting a class of new seed solutions. Some new kinds of periodic soliton structutres, ring form soliton structures and curvilinear soliton structures are revealed by selecting the arbitrary functions appropriately. These structures, which can not be obtained from the formula commonly used in literature, are first reported.
A new method to construct Weierstrass elliptic function solutions for soliton equations
Authors: Li De-Sheng  , Zhang Hong-Qing  ,   (1)大连理工大学应用数学系，大连  116024; (2)燕山大学数学系，秦皇岛  066004;大连理工大学应用数学系，大连  116024
Published: December 2020

Utilizing the equation that has Weierstrass elliptic function solutions, we have obtained two groups of new solutions of projection Riccati equation. Because the projection Riccati equation can be used to solve nearly all kinds of non-linear evolution equations, thus we have given a method for constructing. Weierstrass elliptic function solutions for nearly all equations with soliton solutions.
Multi-party multi-level quantum key distribution protocol based on entanglement swapping
Authors: Yang Yu-Guang  , Wen Qiao-Yan  , Zhu Fu-Chen  ,   (1)北京邮电大学理学院，北京  100876; (2)现代通信国家级重点实验室，成都  610041
Published: December 2020

A multi-party multi-level quantum key distribution protocol based on entanglement swapping is proposed. A perfect complete orthonormal basis of the bi-party three-level systems is first constructed. By using this basis and swapping the entanglement, bi-party quantum key distribution is realized. In addition, three-level can be generalized to multi-level and bi-party to multi-party,i.e., multi-party multi-level quantum key distribution based on entanglement swapping can be achieved. Using entanglement swapping and multi-level key distribution can significantly increase the efficiency of the detection of eavesdropping, the key generation rate and the information flux.
Dynamics of many particles in the urn model
Authors: Chen Bo  , Tong Pei-Qing  ,   (1)南京师范大学物理科学与技术学院,南京  210097; (2)南京邮电大学通达学院,南京  210003
Published: December 2020

We study the behavior of many particles moving in the 2-urn and 3-urn systems driven by a stochastic heat bath. The velocities and the positions of the particles are calculated through noise activated 1-D Langevin function. We find the time in which the system is in equilibrium becomes longer than the time in which the system is in non-equilibrium as the bath temperature increases. The velocity distribution of the particles is always Gaussian. The effective temperature T2 characterizing non-equilibrium state obeys the power law with the restitution coefficient r.
Research on parameters of higher-order transverse magnetic modes in cylindrical coaxial cavity resonator
Authors: Dong Yu-He  , Ding Yao-Gen  , Xiao Liu  ,   (1)中国科学院电子学研究所,北京  100080; (2)中国科学院电子学研究所,北京  100080;中国科学院研究生院,北京  100039; (3)中国科学院电子学研究所,北京  100080;中国科学院研究生院,北京  100039;内蒙古科技大学数理系,包头  014010
Published: December 2020

The inter-related parameters of higher order transverse magnetic (TM) modes in coaxial cavity are calculated and analyzed. It is found that TMn10 modes have large mode intervals. There exists a maximum characteristic impedance while keeping the specific cavity outer radius constant. Large cross-section cavity can be employed in higher frequency range. The solutions show good agreement with the results simulated by ISFEL 3-demention and HFSS, softwares used for electromagnetic simulation. The results calculated can serve as a database from which the optimum seeking in design can be gotten instantly instead of the time-consuming simulation by trial and error.
Influences of optical breakdown on stimulated Brillouin scattering
Authors: Hasi Wu-Li-Ji  , Lü Zhi-Wei  , He Wei-Ming  , Li Qiang  , Ba De-Xin  ,   (1)哈尔滨工业大学光电子技术研究所,哈尔滨  150001; (2)哈尔滨工业大学光电子技术研究所,哈尔滨  150001;内蒙古民族大学化学学院,通辽  028043
Published: December 2020

Avalanche ionization model is introduced to the coupled stimulated Brillouin scattering (SBS) equations. Numerical simulation of SBS energy reflectivity as a function of pump intensity is made with and without the optical breakdown factor in the equations. In the experiment, purified and unpurified CCl４ media are studied with an Nd:YAG laser system with Q switch, the results are found to agree well with the numerical solutions. It is observed that under conditions that the optical breakdown does not occur, the energy reflectivity increases nonlinearly with pump intensity until reaching a certain value above which it tends to grow slowly. In cases with the breakdown, the energy reflectivity first increases nonlinearly with the pump intensity to a peak value and then decreases dramatically as optical breakdown occurs. The stability of energy reflectivity in the cases without optical breakdown is obviously better than cases otherwise.
Talbot effect of a grating under chirped ultrashort pulsed laser illumination
Authors: Wang Huai-Sheng  ,   上海电力学院数理系，上海  200090
Published: December 2020

The Fresnel diffraction equation of a grating under chirped ultrashort pulsed laser illumination is given through Fourier spectrum analysis, and the Talbot effect of the grating is studied using the equation. Numerical calculation shows that the intensity distribution of the grating at Talbot distances is related to both the width and the chirp parameter of the ultrashort pulse. According to the intensity change of the grating, a simple method is put forward to check whether an ultrashort pulsed laser contains chirp information.
Period doubling motion in vertically vibrated granular beds
Authors: Jiang Ze-Hui  , Liu Xin-Ying  , Peng Ya-Jing  , Li Jian-Wei  ,   哈尔滨工业大学物理系，哈尔滨  150001
Published: December 2020

Experiments are performed to investigate the impact interaction between granular bed and container bottom, where the container is vertically vibrated. It is observed that the impact strength, controlled by the normalized vibration acceleration, undergoes a series of period doubling bifurcations, typically in the sequence of period-doubling, period-quadrupling, chaos, period-tripling, period-sextupling, chaos, period-quadrupling, period-octupling, and chaos. A condensed state of particles at the bottom of the container is observed, in which the particles are densely compacted and move as a bulk block in the vertical direction. Based on a completely inelastic bouncing ball model, a possible explanation for the bifurcation phenomena is presented.
Second-order Stokes solutions for internal waves in three-layer density-stratified fluid
Authors: Chen Xiao-Gang  , Song Jin-Bao  , Sun Qun  ,   (1)中国科学院海洋研究所,青岛  266071; (2)中国科学院海洋研究所,青岛  266071;内蒙古工业大学理学院,呼和浩特  010062;中国科学院研究生院，北京  100039
Published: December 2020

In this paper, internal waves in three-layer stratified fluid are investigated by using a perturbation method, and the second-order asymptotic solutions of the velocity potentials and the second-order Stokes solutions of the associated elevations of the interfacial waves are presented based on the small amplitude wave theory. As expected, the first-order solutions are consistent with ordinary linear theoretical results, and the second-order solutions describe the second-order modification on the linear theory and the interactions between the two interfacial waves. Both the first-order and second-order solutions derived depend on the depths and densities of the three-layer fluid. It is also noted that the solutions obtained from the present work include the theoretical results derived by Umeyama as special cases.
Study on the evolution of Au heteroepitaxial islands on Cu(001) by molecular dynamics simulation
Authors: Meng Yang  , Zhang Qing-Yu  ,   大连理工大学三束材料改性国家重点实验室，大连  116024
Published: December 2020

Molecular dynamics simulation was used to relax the heteroepitaxial Au islands in monolayer on Cu(001) substrate in the initial stage of film growth. The evolution of the morphology and local pressure of the heteroepitaxial Au islands as well as the adhesive energy to the substrate have been analyzed. The simulation results show that a pseudo-morphologically strained Au island is formed when the heteroepitaxial Au island is not larger than 7×7. When the heteroepitaxial Au island is as large as 8×8, however, a misfit dislocation induced by the stress, which results from the mismatch in the interface, appears. The number of the misfit dislocations increases with increasing scale of the heteroepitaxial Au island, and moreover, crossing dislocations and vacancies can be observed in large heteroepitaxial Au islands. The analysis results of the local pressure map show that the difference of the neighborhood results in the difference of the stress of the atoms in the heteroepitaxial Au islands. Furthermore, the psudo-morphologically strained Au islands are the results of the different local pressure of Au atoms in the heteroepitaxial Au islands. On the other hand, we found that the misfit dislocations lead to the decrease of the adhesive energy of the mismatched atoms to the substrate, and the adhesion of other atoms increases relatively.
Correlation between optical spectrum, electron paramagnetic resonance spectrum and local structure of MnF2:Mn2+
Authors: Xie Lin-Hua  , Qiu Min  ,   四川师范大学固体物理研究所，成都  610066
Published: December 2020

The optical luminescence spetrum and electron paramagnetic resonance hyperfine constant of MnF2:Mn2+ are given a unified explaination on the basis of semi-self consistent field d-orbit theory and a new method of determination of bond length from hyperfine constant. The bond length of Mn—F in MnF2:Mn2+ crystal is determined as 0.2124±0.0010nm.
Electron holography investigation on the barrier structures of Co based magnetic tunnel junctions
Authors: Zhang Zhe  , Zhu Tao  , Feng Yu-Qing  , Zhang Ze  ,   (1)中国科学院物理研究所，北京  100080; (2)中国科学院物理研究所，北京  100080;北京工业大学固体微结构与性能研究所，北京  100022
Published: December 2020

The barrier potential profiles and microstructure of Co based magnetic tunnel junctions (MTJs) annealed up to 340℃ have been studied by electron holography (EH) and high resolution electron microscopy. The EH results reveal that the annealing process can well improve the quality of interfaces between barrier and ferromagnetic electrodes, and of AlOx barrier itself, which are responsible for the improvement of tunneling magnetoresistance in MTJs after anneal at 280℃.
Magnetocrystalline anisotropy and spin-reorientation transition of intermetallic compound HoMn6Sn6
Authors: Guo Guang-Hua  , Zhang Hai-Bei  ,   中南大学物理科学与技术学院，长沙  410083
Published: December 2020

The molecular field theory of exchange interaction has been applied to investigate the spin-reorientation transition in intermetallic compound HoMn6Sn6. The theoretically calculated temperature dependence of easy magnetization direction is in good agreement with experimental data. The temperature dependence of magnetocrystalline anistropic constants of Ho ion K1R and K2R have been calcullated in the framework of single ion model. It is shown that the fourth-order crystal field parameter B04 and the corresponding second-order magnetocrystalline anistropic constant K2R of Ho ion have to be taken into account in order to explain the spin-reorientation transition. The competition between K2R and K1R plays an important role in the spin-reorientation transition in HoMn6Sn6.
Temperature effect on the adsorption, diffusion and initial growth mode of ZnO/Al2O3(0001) from first principles
Authors: Yang Chun  , Yu Yi  , Li Yan-Rong  , Liu Yong-Hua  ,   (1)电子科技大学微电子与固体电子学院，成都  610054; (2)四川师范大学化学学院，成都  610068; (3)四川师范大学计算机软件重点实验室，成都  610068;电子科技大学微电子与固体电子学院，成都  610054; (4)中国工程物理研究院化工材料研究所，绵阳  621900
Published: December 2020

A heteroepitaxial growth model of the ZnO film on sapphire(0001) is simulated using the plane wave ultrasoft pseudo-potential method based on density functional theory. It is found that interfacial atoms have different diffusivity at 400,600 and 800℃. The temperature has a decisive effect on the surface and interface structures of ZnO/α-Al2O3(0001) and on the growth mode of ZnO thin films. In the whole process of the adsorption and growth of ZnO, the diffusivity of O atoms is higher than that of Zn, and the interlayer diffusion has an important role in the homogeneous growth of the thin films. There exist two growth modes of ZnO on sapphire (0001), which is further demonstrated by theoretical calculation. The growth mode at about 400℃ has the character of mainly spiral-twisted growth with Zn hexagonal symmetry structure, and it is favorable for forming the Zn-terminated surface. In the case of 600℃, a regular in-plane growth is observed, which facilitates the O-terminated surface of the nO thin film. It can be concluded from the calculation that the number of Zn vacancies is greater than that of O in the atomic layer of ZnO film near the α-Al2O3(0001) substrate surface.
Surface study of zirconium implanted with yttrium and lanthanum
Authors: Peng De-Quan  , Bai Xin-De  , Pan Feng  , Sun Hui  ,   清华大学材料科学与工程系，北京  100084
Published: December 2020

Zirconium substrates were implanted with yttrium and lanthanum ions with a fluence ranging from 1016/cm2 to 1017/cm2 at approx 130℃, using a metal vapor vacuum arc source at an acceleration voltage of 40kV. The surfaces of the implanted samples were then analysed. The valence states of elements in the implanted surface layer were analysed using x-ray photoelectron spectroscopy, showing that yttrium exists in the form of Y2O3, and lanthanum exists in the form of La2O3. Depth distributions of elements in the implanted surface of samples were obtained by Auger electron spectroscopy, showing that the thickness of oxide film on zirconium substrate increases with increasing implantation fluence, and when the fluence of 1017/cm2 was used, the maximum thickness of the oxide film was obtained. Rutherford backscattering indicates that a profile distribution depth of ～30nm of La appears in Zr, which also indicates that a serious sputtering occurred during the (La+Y) 1017/cm2 implantation.
Comparison of field emission of carbon, carbon nitride and boron carbon nitride nanotubes
Authors: Li Qiang  , Liang Er-Jun  ,   (1)郑州大学物理工程学院，材料物理教育部重点实验室，郑州  450052; (2)郑州大学物理工程学院，材料物理教育部重点实验室，郑州  450052;东华大学应用物理系，上海  200051
Published: December 2020

Carbon,CNx and BCN nanotubes were synthesized by pyrolysis at 860℃ and purified. Thin films of the purified samples were fabricated by a screen-printing method. The field emission effect of these films was compared. It was found that the turn-on field was 2.22，1.1 and 4.4V/μm,and the current density at 5.7V/μm was 1400，3000 and ＜50μA/cm2 for C, CNx and BCN nanotubes,respectively. The electron field emission property of the CNx nanotubes was better than the carbon nanotubes while that of BCN nanotubes was the worst. The origin of the differences in field emission of these films was explained.
Selective effect to frequency and direction of gravitational waves on gaussian beam resonance system
Authors: Shi Dong-Ping  , Li Fang-Yu  , Zhang Yi  ,   (1)成都市新都区委组织部，成都  610500; (2)重庆大学理论物理研究所，重庆   400044; (3)重庆文理学院 物理与信息工程系，重庆  402168
Published: December 2020

Gaussian beam resonance system (GBRS) opens a very important window for detection of relic stochastic high frequency gravitational waves (HFGWs) of early universe. The results of calculation show that the first-order perturbation photon flux produced by this system has no observable effect when the GWs frequency is different from that of Gaussian beam. The first-order perturbation photon flux produced by GBRS will be reduced by several orders of magnitude when the propagation direction of GWs is different from that the positive direction of the symmetrical axis of Gaussian beam, i. e., GBRS only responds to relic HFGWs that propagate along a specific direction. Therefore, GBRS have a useful selective effect with respect to the frequency and propagation direction of relic HFGWs.
Synchronization of Liu chaotic system based on linear feedback control and its experimental verification
Authors: Wang Fa-Qiang  , Liu Chong-Xin  ,   西安交通大学电气工程学院，西安  710049
Published: December 2020

Synchronization of Liu chaotic system is studied. Based on the characteristic of the chaotic system and linear feedback control method, the range of the controller parameter for synchronization is derived, the results of simulation and experiment are provided to show the effectiveness of the proposed method.
Effects of high magnetic fields on the distribution of solute elements in Al-alloys
Authors: Pang Xue-Jun  , Wang Qiang  , Wang Chun-Jiang  , Wang Ya-Qin  , Li Ya-Bin  , He Ji-Cheng  ,   (1)东北大学材料电磁过程研究教育部重点实验室，沈阳  110004; (2)沈阳铸造研究所，沈阳  110021
Published: December 2020

The solidified structure of solute elements is important for the quality and the properties of alloys. In the present study, the solidification behavior of aluminum alloys is studied under various high magnetic field conditions, and the influences of uniform and gradient magnetic fields with different intensities and directions on the distribution and the morphology of solute elements of Al-Cu and Al-Mg alloys are investigated. It is found that because of the difference in the electromagnetic forces acting on Cu element and Mg element which have different physical properties in the matrix, the distributions of Cu element and Mg element are the opposite both in the matrix crystallites and in grain boundaries under high static magnetic field, and not only the content but also the distributions of Cu and Mg elements are obviously different under gradient magnetic field. This paper offers a reference to control the solidification structure of solute elements whose physical properties are different in alloys under high magnetic fields.
Digital image correlation method for the analysis of 3-D internal displacement field in object
Authors: Wang Min  , Hu Xiao-Fang  , Wu Xiao-Ping  ,   中国科学技术大学，中国科学院材料力学行为和设计重点实验室，合肥  230026
Published: December 2020

In this paper, the digital image correlation method for the analysis of 3-D displacement field is firstly presented. The 3-D displacement field caused by internal microstructures evolution is obtained by correlative calculation of digital images taken before and after deformation of the object. The 3-D searching window, correlation function and the fitted function of correlation coefficient are obtained. The numerical simulation results confirmed this technique. The precision of displacement measuvement is 0.02 pixel.
Multi-window frequency-tunable electromagnetically induced transparency
Authors: Yang Li-Jun  , Zhang Lian-Shui  , Li Xiao-Li  , Li Xiao-Wei  , Guo Qing-Lin  , Han Li  , Fu Guang-Sheng  ,   河北大学物理科学与技术学院,河北保定  071002
Published: December 2020

Electromagnetically induced transparency (EIT) resonance is obtained in a Λ three-level configuration when the coupling field and the probe field satisfy the two-photon resonance condition. When an additional microwave field drives the transition between two low levels of the Λ three-level system the EIT is observed to split into multiple EITs. In this paper we present a theoretical study of this effect. The results show that the EIT resonance can be split into triplet and the spectral positions of EIT windows is determined by the intensity and the frequency of the microwave field. Therefore, a microwave field can be used to open more than one EIT windows and the EIT frequency tuning can be realized by controlling intensity and frequency of the microwave field.
Influence of external cavity feedback on the oscillating characteristics of a semiconductor laser
Authors: Liu Chong  , Ge Jian-Hong  , Chen Jun  ,   浙江大学现代光学仪器国家重点实验室，杭州  310027
Published: December 2020

Through the introduction of effective reflectivity, the influence of external optical feedback on the oscillating characteristics of a semiconductor laser is discussed, such as the threshold gain, laser frequency and output power, according to the self-consistency condition and the photon and carrier density ratio equation. In the experiment, the threshold current of a laser diode decreased from 420mA to 370mA with external cavity feedback and the slope efficiency increased. The output power obtained by theoretical simulation agrees well with the experiment results.
Material growth and device fabrication of highly strained InGaAs/InGaAsP long wavelength distributed feedback lasers
Authors: Pan Jiao-Qing  , Zhao Qian  , Zhu Hong-Liang  , Zhao Ling-Juan  , Ding Ying  , Wang Bao-Jun  , Zhou Fan  , Wang Lu-Feng  , Wang Wei  ,   中国科学院半导体研究所 光电子研究发展中心，北京  100083
Published: December 2020

1.6—1.7μm highly strained InGaAs/InGaAsP distributed feedback lasers was grown and fabricated by low pressure mentalorganic chemical vapor deposition. High quality highly strained InGaAs/InP materials were obtained by using strain buffer layer. Four pairs of highly strained quantum wells were used in the devices and carrier blocking layer was used to improve the temperature characteristics of the devices. The uncoated 1.66μm and 1.74μm lasers with ridge wave guide 3μm wide have low threshold current (14mW at 100mA). In the temperature range from 10℃ to 40℃, the characteristic temperature T0 of the 1.74μm laser is 57K, which is comparable to that of the 1.55μm-wavelength InGaAsP/InP-DFB laser.
Optimization of optical design of the master amplifier in multi-pass off-axis amplification system
Authors: Wang Fang  , Zhu Qi-Hua  , Jiang Dong-Bin  , Zhang Qing-Quan  , Deng Wu  , Jing Feng  ,   中国工程物理研究院激光聚变研究中心，高能高密度等离子体物理国家实验室，绵阳  621900
Published: December 2020

Using the aberration control and ghost image tracing theory and the idea of partial optimizing, integration and complete optimizing, the optimization of optical design of the master amplifier in a 4-pass off-axis amplification system is accomplished. The work provides guidance for the system optical design in the high power laser facility.
Stimulated Raman cascade-into-photon condensation and ultra-intense EM solitons in laser plasma interaction
Authors: Li Bai-Wen  , Zheng Chun-Yang  , Song Min  , Liu Zhan-Jun  ,   (1)北京应用物理与计算数学研究所,北京  100088; (2)中国农业大学理学院物理系，北京  100083
Published: December 2020

Stimulated Raman scattering, stimulated Raman cascade and the transition from Raman cascade into photon condensation, induced by linearly-polarized intense laser beam interacting with underdense collisionless homogeneous plasmas, are studied by particle simulations. It is found that, at appropriate laser amplitude and plasma condition, a large-amplitude relativistic EM soliton is formed due to the strong photon condensation. The standing, backward- and forward-accelerated large-amplitude relativistic electromagnetic solitons induced by intense laser pulses in underdense collisionless homogeneous plasmas are studied by particle simulations. In addition to the inhomogeneity of the plasma density, we found that the acceleration of the solitons depends upon both the laser intensity and the plasma length. The electromagnetic frequency of the solitons is about one-half of the unperturbed electron plasma frequency. The transverse electric, magnetic and electrostatic fields have half-, one- and one-cycle structure in space, respectively.
Analysis and design of triaxial output cavity in a relativistic klystron amplifier
Authors: Huang Hua  , Meng Fan-Bao  , Fan Zhi-Kai  , Li Zheng-Hong  , Fang Xiang  ,   (1)四川绵阳市电业局，绵阳  621000; (2)中国工程物理研究院应用电子学研究所，绵阳  621900
Published: December 2020

This paper discusses the space-charge-limited current and its energy distribution in the coaxial drifting pipe. In order to bypass the potential depression problem, the triaxial output cavity of relativistic keystron amplifier was implemented. The triaxial output cavity was designed and simulated. A hollow electron beam of 590kV, 5kA generates 1GW rf power in S band klystron amplifier using the triaxial output cavity. The efficiency is about 35%, which is 9% bigger than that of the coaxial output cavity. The results agree well with the experiment.
Effect of interface and preferred orientation on the hardness of TiN/ZrN multilayers
Authors: Xu Xiao-Ming  , Wang Juan  , Zhao Yang  , Zhang Qing-Yu  ,   大连理工大学三束材料改性国家重点实验室,大连  116024
Published: December 2020

TiN/ZrN multilayers were fabricated using reactive radio-frequency magnetron sputtering methods. X-ray diffraction analysis was used to determine the modulation structure of the multilayers. Using high-resolution transmission electronic microscopy, the interface was found to be a mixed layer of 2—3 nm in thickness. The nano-indentation measurement showed that the hardness of TiN/ZrN multilayers varied with the modulation period. Both the hardness and elastic modulus had their maximums for the multilayer with a modulation period of about 15.24 nm. The enhancement in hardness is discussed with different hardening mechanisms. The interface states and preferred orientation are assumed to be the main causes of the enhancement of TiN/ZrN multilayers in hardness.
Quasicrystals fabricated by holographic lithography
Authors: Wang Xia  , Wing Yim-Tam  ,   (1)青岛科技大学数理学院光电子科技研究所,青岛  266061; (2)香港科技大学物理系纳米科技研究所，香港
Published: December 2020

In this paper, we report the use of combining holography and photo-induced polymerization techniques to fabricate 2D mesoscale Penrose quasicrystals using 5 coherent beams. The effects of exposure dosage and polarizations of laser beams on the structures are studied. It is demonstrated that the air holes in the 2D quasicrytals could be as small as 0.1μm for high exposure dosage samples. This setup can be used to fabricate versatile 2D mesoscale quasicrystals, and may also shed light on extending this method to 3D quasicrystals. Here we offer a novel method to fabricate quasicrystals which is simpler and cheaper than, if not superior to, the other traditional micro-fabrication methods.
The growth model and experimental validation of size-controlled nanocrystalline silicon
Authors: Liu Yan-Song  , Chen Kai  , Qiao Feng  , Huang Xin-Fan  , Han Pei-Gao  , Qian Bo  , Ma Zhong-Yuan  , Li Wei  , Xu Jun  , Chen Kun-Ji  ,   南京大学物理系，固体微结构物理国家重点实验室，南京  210093
Published: December 2020

According to the processes of nucleation and growth of nanocrystalline silicon (nc-Si) with shape changing from sphere-like to disc-like in the a-SiNx/a-Si:H/a-SiNx sandwich structure or a-Si :H/a-SiNx multilayer structure, we have proposed the theoretical model of constrained crystallinzation based on the classical thermodynamics, in which the increase of the interfacial energy between nc-Si and a-SiNx causes the growth of nc-Si to halt, and concludes the critical thickness of a-Si sublayer (34 nm) for constrained crystallization, The model of constrained growth has been validated in a-SiNx/nc-Si/a-SiNx sandwich and nc-Si/a-SiNx multilayer structures formed by laser annealing and thermal annealing.
Electromigration in Al interconnects and the challenges in ultra-deep submicron technology
Authors: Zhang Wen-Jie  , Yi Wan-Bing  , Wu Jin  ,   (1)上海宏力半导体制造有限公司,上海  201203; (2)中国科学院上海微系统与信息技术研究所,上海  200050;中国科学院研究生院,北京  100049;上海宏力半导体制造有限公司,上海  201203
Published: December 2020

Electromigration (EM) problem in Al interconnects is one of the most persistent and important challenges in the microelectronic industry. From 1990s, with the scaling down and new processes introduced, ultra-deep submicron (feature size≤0.18 μm) Al interconnects involve more complicated EM issues. In this paper, we summarized the basic formulae of the EM phenomena and got the important flux divergence equations. Based on the equations, the research methods for EM problems were reviewed. The main issues and solutions during the half century of investigation for Al EM challenges were reviewed as well. Finally, the essentials and challenges of current ultra-deep submicron Al EM reliability are analyzed, and some prospective solutions were also proposed.