bluuebunny/crossref_metadata_2025 huggingface dataset:
The measurement of creep rate sensitivity of copper at room temperature by using nanoindentation
Authors: Zhang Jian-Min  , Xu Ke-Wei  ,   (1)陕西师范大学物理学与信息技术学院，西安 710062; (2)西安交通大学金属材料强度国家重点实验室，西安 710049
Published: December 2020

A new nanoindentation creep test, i.e. a steady-state loading segment followed by the constant load for long period of time, has been proposed by combining a constant loading rate divided by the load (const.P·/P) with a constant load test (const.P). The method is applicable not only to the materials with lower melting temperature and higher creep ability, but also to those materials with higher melting temperature and lower creep ability and an indentation size effect. The strain rate sensitivity m of Cu at room temperature determined by the method is about 0.01. It is also found that the previous loading schemes, including the values of the P·/P used during loading segment and the maximum depths h-max at the end of the loading segment, have no obvious influence on the values of the strain rate sensitivity m.
Valence band photoemission of Yb2.75C60
Authors: Li Hong-Nian  , He Shao-Long  , Li Hai-Yang  ,   浙江大学物理系，浙江大学中心实验室，杭州 310027
Published: December 2020

Valence-band electronic density of states of Yb2.75C60 thin films was measured by the ultraviolet photoemission spectrum technique. The phase-pure Yb2.75C60 sample was characterized by the C 1s XPS measurements. The result indicates Yb2.75C60 has no Fermi edge and thus is semiconductor. The hybridization between 6s state of Yb and the LUMO band of C60 cannot be considered to be negligible. Some Yb 6s electrons occupy the Yb-C60 covalent band in Yb2.75C60.
From quantum spectra to classical orbits: the rectangular billiards
Authors: Lu Jun  , Du Meng-Li  ,   中国科学院理论物理研究所，北京 100080
Published: December 2020

A new quantum spectrum function is defined using the eigenvalues and eigenfunctions of the system considered. We study the two-dimensional rectangular billiard,and find that the Fourier transform of the spectrum function reveals the classical orbits from one point to another.
A general scalar chaotic signal synchronization system and its controller via backstepping design
Authors: Gao Jin-Feng  , Liang Zhan-Hong  ,   郑州大学电气工程学院，郑州 450002
Published: December 2020

A general scalar chaotic signal synchronization system is proposed in this paper. For the system in the “strict-feedback" form with variant parameters and variant weights of artificial control terms, a feedback controller and associated parameter adaptive laws are constructed via adaptive backstepping design with tuning functions. Using the controller and parameter adaptive laws proposed in this paper, the output of the general system asymptotically synchronizes with the output of any chaotic system with a known structure. Both theory analysis and computer simulation results illustrate the validity of the general scalar chaotic signal synchronization system and its controller.
The measurement of square resistance for microarea by square four-probe techniques and using a modified Rymaszewski’s formula
Authors: Liu Xin-Fu  , Sun Yi-Cai  , Zhang Yan-Hui  , Chen Zhi-Yong  ,   河北工业大学微电子技术与材料研究所，天津 300130
Published: December 2020

The sheet resistance for a microarea in a large silicon wafers was measured by using a modified Rymaszewski's formulas for a square four-point probe technique. An improved Rymaszewski's formulas was deduced taking into account the shift of probes in square four-point probe measurement. The equation of resistivity for square four-point probe measurement when there were shifts of the probes and there was no shift of the probes was deduced theoretically. A possible error produced by the shift of the probes was analyzed in theory and expressed with graphs. The effect upon measuring results arising from the shift of probes was also discussed. Practical-measurement of a specimen has been tested using a self-established equipment of square four-point probes. An equal-value-line graph was plotted for the measurement-results.
Effect of the ratio of TMIn flow to group Ⅲ flow on the properties of InGaN/GaN multiple quantum wells
Authors: Zhang Ji-Cai  , Wang Jian-Feng  , Wang Yu-Tian  , Yang Hui  ,   (1)中国科学院半导体研究所，集成光电子国家重点实验室，北京 100083; (2)中国科学院半导体研究所，集成光电子国家重点实验室，北京 100083;武汉大学物理系，武汉 430072
Published: December 2020

Triple-axis x-ray diffraction (TXRD) and photoluminescence (PL) spectra are used to assess the influence of the ratio of TMIn flow to group Ⅲ flow on structural defects, such as dislocations and interface roughness, and optical properties of multiple quantum wells(MQWs). In this paper the mean densities of edge and screw dislocations in InGaN/GaN MQWs are obtained by ωscan of every satellite peak of (0002) symmetric and (1012) asymmetric diffractions. At the same time, the interface roughness is measured by the radio of the full width at half maximum of satellite peaks to the peak orders. The experimental results showed that the density of dislocation, especially of edge dislocation, and interface roughness increase with the increase of the ratio, which leads to the decrease of PL properties. It also can be concluded that the edge dislocation acts as nonradiative recombination centers in InGaN/GaN MQWs. Also noticed is that the variation of the ratio has more influence on edge dislocation than on screw dislocation.
Casimir effect of the Maxwell-Chern-Simons field for two non-parallel lines boundary
Authors: Bai Zhan-Wu  ,   华北电力大学应用物理系,保定 071003
Published: December 2020

Based on the Faddeev formalism of path-integral quantization for a constrained Hamiltonian system, the Casimir effect between two non-parallel lines in the (2+1)-dimensional space is calculated by using conformal mapping and Plana summation formula in the theory of complex variable function. Without introducing any cutoff of parameter, the finite analytical expression is obtained.
On the mechanism of both the radiative production of glueball and the annihilation into electron-positron pair in J/ψ decays
Authors: Peng Hong-An  , Duan Chun-Gui  , Yan Zhan-Yuan  ,   (1)北京大学物理学院，北京 100871; (2)河北师范大学物理系，石家庄 050016;中国科学院高能物理研究所，北京 100039; (3)华北电力大学应用物理系，保定 071003
Published: December 2020

Based on the character in which both the intermediate and final states are intimately related with the vacuum properties of strong-interactions,we have discussed from an alternative point of view the processes of both the radiative production of glueball and the annihilation into electron-positron pair in J/ψ decays.Using the modified field theory model of pomeron in high-energy soft strong processes and the consequent hypothesis of the maximum non-perturbative strong interaction as well as the relevant changes of parameters of the model connecting with the large inner-structure difference between light and heavy constituent quarks,we proposed another mechanism for these two decay processes and calculated their partial width.The coupling constant between the glueballs and the non-perturbative gluons has been estimated.
Phase evolution and electronic states ofRb-intercalated C60 single crystals
Authors: Li Hong-Nian  ,   浙江大学物理系，杭州 310027
Published: December 2020

Rb-intercalated C60 thin film was prepared on the cleaved (111) surface of C60 single crystal under the ultra-high-vacuum condition. Phase evolution was studied by the synchrotron radiation photoemission technique. The energy distribution curves for the solid solution phase, Rb1C60 and Rb3C60 phases were observed. After the Rb3C60 thin film with a thickness of nanometers has formed on the surface layers of the C60 single crystal, the excess depositions of Rb do not induce the bulk-like fcc to bct or bcc structure transitions at room temperature. The large size of C60 molecule offers the surface vacancies for the formations of Rb4C60 and Rb5C60 adsorption phases that are further verified by Rb 3d core-level photoemission measurements. Valence band photoemission results exhibit that the surface phases are metallic.
The theoretical study on the decay processes of the 4d core excited states of Cs Ⅳ
Authors: Ding Xiao-Bin  , Dong Chen-Zhong  , Stephan Fritzsche  ,   (1)Department of Physics,University of Kassel,D-34132 Kassel,Germany; (2)西北师范大学物理与电子工程学院,兰州 730070; (3)西北师范大学物理与电子工程学院,兰州 730070;兰州重离子加速器国家实验室原子核理论研究中心,兰州 730000
Published: December 2020

By including the electron correlation and the relaxation effects,the energy level structures of the 4d core excited configuration 4d9 5s25p5,final radiative configuration 4d105s25p4 and final Auger configurations 4d105s25p3 and 4d105s15p4 of the Cs Ⅳ ion and all possible decay dynamic processes related to these configurations are systematically studied using multi-configuration Dirac-Fock method. The present study not only provides satisfactory results for the radiative transition energies,oscillator strengths and line widths in comp arison with the existing semi-empirical calculations and related experiments,but also predicts some dominant features of the Auger electron spectrum emitted by the Auger decay process of the 4d95s25p5 core excited states.
Molecular dynamics study of the structure changes in a high-angle Cu grain boundary by heating and quenching
Authors: Zhang Lin  , Wang Shao-Qing  , Ye Heng-Qiang  ,   中国科学院金属研究所，沈阳材料科学国家（联合）实验室，沈阳 110016
Published: December 2020

The structure changes of a Cu Σ=5（310）/［001］ symmetrical tilt grain boundary are investigated using the molecular dynamics method by heating and quenching. The simulated results showed that with increasing temperature,there are structure changes of the grain boundary. At a temperature significantly below the bulk melting point of copper,the grain boundary undergoes a structure change,and there exists the crystal-melt coexistence in the grain boundary zone. The grain boundary structures can be changed by quenching,which are compared to those at the same temperatures by heating.
Lattice models of the optimal traffic current
Authors: Xue Yu  ,   广西大学物理系，南宁 530004
Published: December 2020

Based on the lattice model of traffic flow, the lattice models which consider the next-nearest-neighbour flow on traffic and pay attention to the following vehicle as well as the preceding vehicle are presented, respectively. The stability criterion is derived by the linear stability analysis. The evolution of density wave has been investigated analytically with the perturbation method. The results show that the occurrence of traffic jamming transitions is described by the kink solution of the modified KdV equation. The theoretical results are in good agreement with the simulation. Moreover, the simulation indicates that the lattice models considering the next-nearest-neighbour interaction can stabilize the traffic flow, but the other model is just in opposition to the former model.
Fluorescence correlation spectroscopy with saturated excitation
Authors:   (1)清华大学物理系，原子分子纳米科学教育部重点实验室,北京 100084; (2)清华大学物理系，原子分子纳米科学教育部重点实验室,北京 100084;清华大学深圳研究生院,深圳 518057
Published: December 2020

In this paper,we study the errors caused by an intense excitation beam in fluorescence correlation spectroscopy (FCS). Saturated excitation induced by an intense excitation beam will alter the spatial distribution function of the laser-induced fluorescence; therefore it changes the results of FCS measurements. Using the theory for saturated excitation,we derived a general expression for the effective detection volume as a function of the excitation laser intensity. Quantitative relations between the particle number and diffusion time,both obtained from FCS measurements,and the excitation laser intensity are established and used to remove the systematic error due to saturated excitation. The success of this technique is demonstrated in both Monte-Carlo simulations and experiments.
Enhancement of stimulated Raman scattering of minority species of binary mixture in pendant drops by dye lasing gain
Authors: Pu Xiao-Yun  , Yang Rui  , Wang Ya-Li  , Chen Tian-Jiang  , Jiang Nan  ,   云南大学物理系,昆明 650091
Published: December 2020

The enhancement of stimulated Raman scattering (SRS) of minority species of binary mixture is demonstrated in pendant drops by overlapping the Stokes wavelengths of the Raman modes of minority species with Rhodamine 640 dye lasing gain.The limit of detectable concentration for the minority species,methanol in methanol-ethanol and ethanol in ethanol-water mixtures,is greatly reduced. Based on the theory of SRS,the mechanism for enhancing SRS of minority species is explained.
The optical tomography of tissues by a δ sound field
Authors: Zhang Hang  ,   浙江工业大学应用物理系，杭州 310032
Published: December 2020

A new method for realizing the optical tomography of bio-tissue by using a δ sound field and a near infrared laser is presented. A δ sound field is cons tructed and is acted upon the tissue, and this causes some variations of optical properties at the action spot . A perturbation of the light intensity distribution on the tissue surface is measured. The inherent relations between the perturbation and the variations of optical properties are discussed. The optical property distribution in the tissue volume can be extracted from the light distributions on the tissue surface by scanning the action spot at the layer to be constructed. The present method is useful for clinic applications and diagnoses of breast cancers at early stage.
Angular and wavelength selectivity of band gaps of holographic photonic crystals for different polarizations
Authors: Li Rong  , Ren Kun  , Ren Xiao-Bin  , Zhou Jing  , Liu Da-He  ,   北京师范大学物理系，应用光学北京市重点实验室，北京 100875
Published: December 2020

The angular and wavelength selectivities of band gaps of holographic photonic crystals were calculated using transfer matrix method for different polarizations.It showed that the width of the band gaps for P-polarization is narrower than that for S-polarization. About the angular selectivity, the changing trends for different polarizations are the same, but with different degree of variations. About the wavelength selectivity, the changing trends for different polarizations are in an opposite way. A \!general Brewster's angle\" is introduced. The theoretical analysis shows that when a beam incident on a photonic crystal just at the general Brewster's angle\", the forbidden band of S-polarization will still exist as it is, while the forbidden band of P-polarization will vanish. Therefore , a \!defect mode\" can be obtained in the forbidden band of S-polarization by i lluminating the photonic crystal with P-polarization beam at the \!general Brews ter's angle\". The experimental results for verifying the theoretical calculatio ns were given.
Principle and analytical description of inside source holography
Authors: Zhu Pei-Ping  , Wang Jun-Yue  , Wu Zi-Yu  , Tian Yu-Lian  , Jia Quan-Jie  , Hu Tian-Dou  , Wu Xiang  , Chu Wang-Sheng  , Li Gang  , Xian Ding-Chang  ,   中国科学院高能物理研究所, 北京 100039
Published: December 2020

The conventional holography met with three unsolvable difficulties,such as coherence of light source,spatial resolution and sensitivity of detector,when applied in atomic imaging. This paper is intended to explain how the inside source holography can overcome all these difficulties,and to investigate the recording and reconstruction procedures of the inside source holography. The reconstruction formula of inside source spherical hologram and the δ-functions describing reconstructed atomic images in spherical-symmetrical and energy-irrelevent approximations of atomic scattering factor are deduced
Preparation of Schr?dinger cat state via a mesoscopic LC circuit
Authors: Ji Ying-Hua  , Luo Hai-Mei  , Ye Zhi-Qing  , Wu Yun-Yi  , Chen Ming-Yu  ,   (1)江西师范大学物理与通信电子学院, 南昌 330027; (2)江西师范大学物理与通信电子学院, 南昌 330027;江西省光电子与通信重点实验室,南昌 330027
Published: December 2020

A scheme is presented for preparing the superposition of coherent states,i.e.,Schr?dinger cat states. These states can be generated by the action of an external impulse functional signal on initial vaccum state of a mesoscopic LC circuit. The nonclassical squeezing properties appear in the circuit under the Schr?dinger cat states.
Evolution of the entropy of light field interacting with the V-type three-level atom via intensity-dependent coupling
Authors: Huang Chun-Jia  , He Hui-Yong  , Kong Fan-Zhi  , Fang Jia-Yuan  ,   长沙理工大学物理与电子科学系,长沙 410077
Published: December 2020

The evolution properties of the entropy of a single-mode light field interacting with the V-type three-level atom via intensity-dependent coupling have been studied. The discussion is centered on the influence of detuning and initial photon number on the field entropy evolution. The results show that the behavi or of the field entropy is non-periodic for the cases of small detuning and weak initial light field,being similar to the single-photon Jaynes-Cummings model (JCM). On the contrary,the field entropy evolution is periodic for the cases of large detuning or strong initial light field,being similar to the two-photon JCM
Constructive interference: electromagnetically induced absorption
Authors: Wang Li  , Hu Xiang-Ming  ,   华中师范大学物理系,武汉 430079
Published: December 2020

In this paper we reveal that the constructive interference of atomic coherence on absorption leads to electromagnetically induced absorption,which is in sharp contrast to the case in which destructive interference of atomic coherence gives rise to electromagnetically induced transparency. A four-level atomic system is employed in which three transitions are in N configuration and the middle transition is used as a probe transition. In the dressed states representation the probe transition is split into four transitions that are coupled to each other. The coupling originates from the spontaneous emission of the atomic medium and the spontaneous transfer from excited state coherence to ground state coherence. The former leads to couplings between all transitions with the same sign and to the absorption reduction. The latter results in couplings,of which t wo terms have positive sign and another two have negative sign. It is due to the couplings with positive and negative signs that significant modification of the contribution of dressed coherence to absorption occurs,i.e., absorption inhibition is changed to absorption enhancement.
Cavity field spectrum of a cascade three-level atom interacting with a single-mode field
Authors: Gao Yun-Feng  , Feng Jian  , Wang Ji-Suo  ,   (1)(聊城大学教育传播技术学院,聊城 252059; (2)聊城大学光通信研究所,聊城 252059;中国科学院武汉物理与数学研究所，波谱与原子分子物理国家重点实验室,武汉 430071
Published: December 2020

The cavity field spectrum of a cascade three-level atom interacting with a single-mode field in an ideal cavity is investigated. When the atom is in the upper level and the field is vacuum initially,the number of Rabi peaks changes according to 2→6→4→2→4 with the increase of R=g2/g1,and all Rabi peaks disappear for R1 Three-peak,five-peak or seven-peak structure appear for weak initial fields,and single resonance peak appears for a st rong field. When the atom is in the middle level initially,the cavity field spectrum is of a two-peak structure with R=1 as the spectrum of Jaynes-Cummings model.
Role of selective excitation of dressed populations in lasing without inversion
Authors: Wang Zhen-Hua  , Hu Xiang-Ming  ,   (1)华中师范大学物理系，武汉 430079; (2)华中师范大学物理系，武汉 430079;南华大学数理学院，衡阳 421001
Published: December 2020

Exemplifying the three-level systems in the V configuration, we investigate the role of selective excitation of dressed populations in lasing without inversion. Incoherent driving field transfers population from either of the dressed states to excited state when the level spacing between dressed states produced by the coherent field is much larger than the spectral width of the incoherent driving field. With atomic decay pathways，unidirectional channel of population transfer is formed and selective excitation of dressed populations is established. Employing selective excitation of dressed populations，three severe limits are relaxed. First，it is no longer required that the decay rate of the low-frequency driving transition is larger than that of high-frequency laser transition. Second，the threshold for incoherent driving rate is remarkably lowered. Third，linear gain of the laser without inversion is no longer inversely proportional to the coherent driving field intensity, and the gain is significantly enhanced.
A novel eigenvector method for calculation of optical resonator modes and beam propagation
Authors: Cheng Yuan-Ying  , Wang You-Qing  , Hu Jin  , Li Jia-Rong  ,   华中科技大学激光技术国家重点实验室，武汉 430074
Published: December 2020

In this paper,a novel eigenvector method (EM) for calculation of optical resonator modes and beam propagation is introduced,in which the new transit matrix of an optical resonator is obtained by dividing the mirror into finite grids based on Fresnel-Kirchhoff diffracted integral equation. Then,the eigenvectors of the transit matrix,representing the multi-mode characteristics of the resonator,can be calculated by solving the matrix eigen-equation. The field distributions inside or outside the resonator,resulting from the known eigenvectors on the resonator mirror,can be derived by EM. The merits of EM include that the consider ably simpler procedure for solution of eigenvectors of the matrix eigen-equation replaces the complicated iteration in traditional methods,and there is no depen dence on the initial field distribution,and a number of modes can be derived on ce and the discrimination capability of the resonator can be evaluated easily. T he example of using EM to simulate the confocal resonator is given,and the calculated results,well matched with the Fox-Li method and Laguerre-Gaussian approx imatie analytical solution,prove that EM is highly effective and reasonable.
Fabrication of dynamic planar waveguide array in SBN:Cr crystals by structure-light irradiation
Authors: Zhao Jian-Lin  , Li Bi-Li  , Zhang Peng  , Yang De-Xing  , Li Zhen-Wei  ,   西北工业大学应用物理系，西安 710072
Published: December 2020

A planar waveguide array, whose structure is similar to a volume phase grating,can be fabricated in a congruent SBN:Cr (Sr0.61Ba0.39Nb2O6:Cr) crystal by irradiation of two-beam interference pattern,and,simultaneously, by applying an appropriate direct electrical field along the c-axis of the crystal. The transversal index profile of the waveguide array is measured in real-time using a Mach-Zehnder interferometer,and the maximum index change in the waveguide region is close to 10-4. The initial guiding tests show that it is feasible to write a dynamic planar waveguide array in the SBN:Cr crystal by using irradiation of period structure-light,due to the rapid response property of SBN:Cr crystals. And the dynamic control of the waveg uide can be realized by switching the writing lights on or off,or adjusting the angle of the two interferent beams. Moreover,the waveguide parameter such as the index profile in the waveguide zone can be effectively controlled by varying the external electric field.
Effect of stimulated Raman scattering pumped by fourth harmonic Nd:YAG laser in methane and analysis of its physical processes
Authors: Tao Zong-Ming  , Zhang Yin-Chao  , Lü Yong-Hui  , Hu Shun-Xing  , Shao Shi-Sheng  , Cao Kai-Fa  , Liu Xiao-Qin  , Yue Gu-Ming  , Hu Huan-Ling  ,   中国科学院安徽光学精密机械研究所大气光学重点实验室，合肥 230031
Published: December 2020

This paper analyzes theoretically various nonlinear phenomena caused by focusing a laser beam into high-pressure gas, and the interaction and interference produced, measures the relationship among output energy, input energy, gas pressure and focal length when the fourth harmonic Nd:YAG laser is focused into the Raman cell filled with methane. Experimental results are in agreement with theoretical ones qualitatively. Based on these we can optimize and use the stimulated Raman scattering.
Effect of spatial phase modulation on propagation of photovoltaic spatial solitons
Authors: Wang Hong-Cheng  , Wang Xiao-Sheng  , She Wei-Long  , Ren Guo-Bin  , Wang Zhi  , Lou Shu-Qin  , Jian Shui-Sheng  ,   (1)北京交通大学光波技术研究所，北京 100044; (2)北京交通大学光波技术研究所，北京 100044;河北大学物理科学与技术学院，保定 071002; (3)中山大学光电材料与技术国家重点实验室，广州 510275
Published: December 2020

Based on the technology of spatial phase modulation, a simple scheme to steer optical Gaussian beams in photovoltaic media is presented. Numerical simulations show that we can realize the self-deflection, soliton like propagation, divergence and splitting of Gaussian beams in photovoltaic media. The relationship between the intensity profile of the incident beam and the modulation parameters is also discussed.
Transport properties and magnetoresistance effect of polycrystalline La0.7Sr0.3MnO3 at low temperatures
Authors: Xi Li  , Ge Shi-Hui  , Yang Xiao-Lin  , Li Cheng-Xian  ,   兰州大学教育部磁学与磁性材料重点实验室,兰州 730000
Published: December 2020

The resistivity and magnetoresistance of bulk polycrystalline La0.7Sr0.3MnO3(LSM), deliberately fabricated to produce nanoscale grains, has been investigated as functions of temperature. With decreasing temperature below room temperature the resistivity (ρ) exhibits a maximum near 250K， below which it displays a “metallic" behaviour. However, ρ exhibits subsequently a minimum near 50K, below which it is well fit by the predictions for the tunneling of conduction electrons through insulating interfacial layers viz. lnρ∝T-1/2, a result interpreted as conduction-electron tunneling between adjacent LSM granules. The minimum of ρ occurs in this particular sample may result from the competition of the tunneling effect and the intrinsic transport mechanism of LSM. The temperature dependence of the associated tunneling magnetoresistance is also reported in this low temperature regime.
Investigation on holographic reconstruction of sound field using wave superposition approach
Authors: Yu Fei  , Chen Xin-Zhao  , Li Wei-Bing  , Chen Jian  ,   合肥工业大学动态测试中心，合肥 230009
Published: December 2020

Nearfield acoustic holography (NAH) based on wave superposition approach (WSA) is proposed and applied to radiation analysis of sound sources with arbitrarily shaped surface. In problem of calculating acoustic radiation, boundary element method (BEM) is realized by discretizing acoustic and position variables on the boundary surface, while WSA is accomplished by superposing wave fields generated by simple sources interior to the radiator. Therefore, there are no problems such as parameters interpolation, singular integration etc. in WSAbased acoustic holography, which are inherent to BEMbased NAH. The principle of WSAbased acoustic holography is easier to understand, and it is more amiable to implement on the computer. The results of the experiment show that satisfactory precision has been obtained in the reconstruction of sound field using WSAbasedacoustic holography.
A link between the turbulent cascade and the dynamics of transition
Authors: Meng Qing-Guo  , Li Rui-Qu  , Li Cun-Biao  ,   (1)北京大学湍流研究国家重点实验室，北京 100871; (2)国家自然科学基金委员会数理学部，北京 100085;北京大学湍流研究国家重点实验室，北京 100871; (3)清华大学工程力学系，北京 100084
Published: December 2020

The transitional primary dynamical processes, which were constructed in the experiment in a transitional boundary layer, were used to make further analysis on the turbulent cascade patterns. The quantitative results obtained from the measurement data in the transitional boundary layer experiment described the link between the turbulent cascade patterns and a sequence of transitional primary dynamics processes. This may be helpful for us to understand the turbulent cascade more deeply.
Angular distribution of hot electrons emitted from ethanol droplets irradiated by ultrashort laser pulses
Authors: Peng Xiao-Yu  , Zhang Jie  , Jin Zhan  , Liang Tian-Jiao  , Zhong Jia-Yong  , Wu Hui-Chun  , Liu Yun-Quan  , Wang Zhao-Hua  , Chen Zheng-Lin  , Sheng Zheng-Ming  , Li Yu-Tong  , Wei Zhi-Yi  ,   (1)中国科学院物理研究所光物理重点实验室，北京 100080; (2)中国科学院物理研究所光物理重点实验室，北京 100080;中国科学院国家天文台，北京 100012; (3)中国人民解放军防化学院，北京 102205
Published: December 2020

The angular distribution and the energy spectrum of hot electrons with energy over 50keV emitted from ethanol droplets irradiated by linearly polarized 150 fs laser pulses at the intensity of 10 16W/cm2 have been measured. The angular distribution of hot electrons is found to be dependent on the laser polarization. Two hot electron jets like double leaves symmetrically with respect to the laser propagation direction are observed within the polarization plane. The maximum energy of the hot electrons is found to be more than 750 keV. A model based on the resonance absorption can be used to interpret the above distribution. The calculation agrees well with the experimental results.
Finite-difference time-domain analysis on radar cross section of conducting cube scatterer covered with plasmas
Authors: Liu Shao-Bin  , Zhang Guang-Fu  , Yuan Nai-Chang  ,   (1)国防科技大学电子科学与工程学院，长沙 410073; (2)国防科技大学电子科学与工程学院，长沙 410073;南昌大学物理系，南昌 330047
Published: December 2020

A PLJERC-FDTD algorithm is applied to the study of the scattering of perfectly conducting cube covered with homogeneous isotropic plasmas. The effects of plasma thickness, density and collision frequency on the radar cross section(RCS) of the conducting cube scatterer have been obtained. The results illustrate that the plasma cloaking can greatly reduce the RCS of radar targets, and the RCS of the perfectly conducting cube scatterer decreases with increasing plasma thickness when the plasma frequency is greatly less than the electromagnetic(EM) wave frequency; the RCS of the perfectly conducting cube scatterer decreases with increasing plasma thickness and plasma collision frequency when the plasma frequency is almost half as much as the EM wave frequency; the effects of plasma thickness and collision frequency on the RCS of the perfectly conducting cube scatterer is small when the plasma frequency is close to the EM wave frequency.
Numerical modeling of supersonic plasma jet
Authors: Yuan Xing-Qiu  , Li Hui  , Zhao Tai-Ze  , Yu Guo-Yang  , Guo Wen-Kang  , Xu Ping  ,   (1)复旦大学现代物理研究所，上海 200433; (2)中国科学技术大学热科学与能源工程系，合肥 230027; (3)中国科学院等离子体物理研究所，合肥 230031
Published: December 2020

Numerical simulation results are presented in this paper concerning the heat transfer and fluid flow within the supersonic plasma jet, which is produced by the converging diverging plasma torch. The full NaiverStokes equations, which take into account the gas viscous effects, temperature and pressure dependent properties, and compressible effects, are employed in this simulation and the PHOENICS software is used to solve the set of nonlinear equations. The shock structure within the supersonic plasma jet is analysed in detail,and the effects of ambient pressure on the jet flow field are studied. Results show that the supersonic plasma flow interacts with the ambient gas and forms a series of compression and expansion waves in the region near the torch nozzle exit.
A study on critical universality of the random-bond Potts models with self-dual quenched randomness
Authors: Ren Hao  , Gu De-Wei  , Pan Zheng-Quan  , Ying He-Ping  ,   (1)杭州成人科技大学,杭州 310006; (2)浙江大学物理系, 浙江近代物理中心,杭州 310027
Published: December 2020

In this paper we present our numerical study on short-time critical dynamics for the q-state random-bond Potts model with self-dual quenched disorders. By exploring the universal power-law scaling behavior, the results of magnetic exponent η and dynamic exponent z are estimated for the q=3 and q=8 cases with two specific disorder distribution functions. Our Monte Carlo simulations show evidence that the results of magnetic exponent η are independent of distribution forms, which verifies the existence of universality for the general quenched random-bond models numerically.
Numerical simulation of tungsten wire-array pinch plasma
Authors: Duan Yao-Yong  , Guo Yong-Hui  , Wang Wen-Sheng  , Qiu Ai-Ci  ,   西北核技术研究所，西安 710024
Published: December 2020

A two-dimensional, three-temperature radiation magneto-hydrodynamics model is applied to the simulation of tungsten wire-array plasma implosion based on the real experimental parameters of the Qiangguang1 generator. The spatial-temporal evolutions of the plasma density and temperature are presented, and the characteristic of the magnetic field and current density is analyzed and summarized. The calculated x-ray power curve is approximately in agreement with the corresponding measured one. All these predicted quantities are conducive to the plas ma diagnoses of Z pinches. In addition, some of physical parameters and numerical schemes related to this simulation are discussed also.
Effects of charging at dielectric surfaces on the characteristics of the sheath for plasma immersion ion implantation
Authors: Li Xue-Chun  , Wang You-Nian  ,   大连理工大学物理系,三束材料改性国家重点实验室,大连 116024
Published: December 2020

Using the one-dimensional dynamic sheath model, the effects of charging at a planar dielectric surface in plasma immersion ion implantation are studied. The temporal evolution of the sheath thickness, the effective potential at the surface of the dielectric and the ion dose accumulated on it are obtained for different plasma densities and dielectric thicknesses. The numerical results demonstrated that due to the charging effects, the plasma density has a profound impact on doping result during plasma immersion ion implantation, but the thickness of the dielectric has no significant effect on it.
Physical effects caused by surface elastic term K13 on nematic-liquid-crystal cells and the detecting scheme about K13
Authors: Guan Rong-Hua  , Huai Jun-Xia  , Liu Jian-Jun  , Yang Guo-Chen  ,   (1)河北工业大学理学院,天津 300130; (2)河北工业大学理学院,天津 300130;河北师范大学物理学院,石家庄 050016; (3)华北电力大学应用物理系,保定 071003
Published: December 2020

Base on successful solution of the problems in judging whether the surface elastic term K13 of nematic liquid crystal exists or not, the equilibrium equation and boundary condition of the director have been obtained by the methods of analytical derivation and numerical calculation. The influence of the surface elastic energy term K13 on the properties of Fréedericksz transition of weak anchoring nematic liquid crystal cell under a magnetic field has been investigated in detail. The results show that the existence of K13 has influence on the free energy of the liquid crystal system so great as to change the property of the transition and induce a first-order Fréedericksz transition. The conditions for this transition are obtained. They depend on the surface elastic energy term K13 besides the structure and material of the system. The method of judging whether K13 term exists or not by Fréedericksz transition has been given.
Temperature coefficient of resistance of VO2 polycrystalline film formed by ion beam enhanced deposition
Authors: Li Jin-Hua  , Yuan Ning-Yi  ,   江苏工业学院信息科学系,常州 213016
Published: December 2020

The polycrystalline VO2 film was directly prepared from V2O5 powder using the modified ion beam enhanced deposition (IBED) method and a suitable annealing. Testing results show that the IBED polycrystalline VO2 film has a single orientation, an obvious phase transition, a compact structure, and favorable processing properties. The temperature coefficient of resistance (TCR) of the film was up to more 4% and adhered hard to the substrate. The mechanism of the IBED film with higher TCR was discussed in detail. The reason why the film has a high TCR could be as follows: the oxygen vacancy and crystalline boundary in the film was decreased due to the IBED technology; with single oriented and dense texture the activation energy of electrical conduction of the IBED polycrystalline VO2 film was closer to the activation energy of VO2 crystalline in semiconductor phase which is higher than that of the VOx films prepared by other methods
Computer simulation of thin-film epitaxy growth
Authors: Zheng Xiao-Ping  , Zhang Pei-Feng  , Liu Jun  , He De-Yan  , Ma Jian-Tai  ,   (1)兰州大学化学化工学院,兰州 730000; (2)兰州大学物理科学与技术学院,兰州 730000; (3)兰州交通大学光电技术与智能控制教育部重点实验室,兰州 730070
Published: December 2020

A three-dimensional kinetic Monte-Carlo technique has been developed for simulating the growth of thin Cu films. The model involves incident atom attachments, diffusion of the atoms on the growing surface, and the detachment of the atoms from the growing surface. Related effects due to surface atom diffusion was taken into account. A great improvement was made on calculation of the activation energy for atom diffusion based on a reasonable assumption of interaction potential between atoms. The results showed that as the substrate temperature is raised or the deposited rate decreased, the diffusion of particles causes the particles grouping into islands (more than three atoms). The higher the temperature or the lower the deposition rate, the larger the size of the islands. Also we observed the island shape transition from two-dimensional islands to three-dimensional ones. There exist three optimum growth temperatures at a given deposition rate, namely Tn at which the nucleation rate is maximum, Tr at which the surface roughness minimizes and Td at which the relative density approaches to saturation. They all increase with the increase of substrate temperature, and these variations almost superpose on each other. The simulation results also showed that the relative density decreases with increasing deposition rate. But the nucleation rate is close to a steadiness at a lower temperature while it increases at a higher temperature. The surface roughness increases at a lower temperature while it decreases at a higher temperature.
The effect of lattice mismatch on the nucleation process of heteroepitaxial growth of ultrathin film
Authors: Wang Xiao-Ping  , Xie Feng  , Shi Qin-Wei  , Zhao Te-Xiu  ,   (1)中国科学技术大学物理系,合肥 230026; (2)中国科学技术大学物理系,合肥 230026;中国科学院结构分析重点实验室,合肥 230026; (3)中国科学院结构分析重点实验室,合肥 230026
Published: December 2020

The effect of lattice mismatch between the substrate and the heteroepitaxial film on the initial process of ultra-thin film growth, such as the nuclear density, the average size of cluster, the scale behavior and the growth mode, is studied by the kinetic Monte-Carlo method. It is found that the negative (positive) mismatch, corresponding to the compressive (tensile) strain, can induce the growth process transferring from the nucleation stage to the intermediate one earlier (later). The larger the mismatch, the more apparent the above behavior. Under the same deposition condition, the negative mismatch can bring about lower nuclear density and larger average cluster size than the positive mismatch does. Furthermore, the nuclear density is found to follow the power law of Ns≈(F/D)χ, andχdecreases from 0.37 to 0.33 while the mismatch changes from –0.04 to 0.02. This behavior indicates that the growth mode of the ultra-thin film changes from including dimer diffusion into excluding dimer diffusion. Additionally, the scale theory of the cluster size is found to be valid even for the heteroepitaxial growth.
Photoluminescent properties of Cu-doped ZnO thin films
Authors: Peng Xing-Ping  , Lan Wei  , Tan Yong-Sheng  , Tong Li-Guo  , Wang Yin-Yue  ,   兰州大学物理系,兰州 730000
Published: December 2020

Zinc oxide films doped with various contents of copper were deposited on silicon (111) substrates by rf reactive sputtering. The photoluminescent(PL) spectra of the ZnO films were measuered at room temperature. Results showed that each of the samples had a blue band at about 435nm (2.85eV) and the intensities of these blue bands were changed with the variation of content and sputtering power. It was observed that there is a stronger blue bi-peak when the power reaches 150W and the copper content is equal to 2.5%, and there is a stronger blue peak at 437?nm when the power was 100?W and copper content is 1.5% on the PL spectra of ZnO films, the latter had a good c axis orientation. We have investigated the PL properties for various Cu-doped contents and different sputtering powers, and the mechanism of blue emission was also discussed in this paper.
Ab initio study of the hydrogen-adsorbed diamond (001) surface
Authors: Yu Yang  , Xu Li-Fang  , Gu Chang-Zhi  ,   (1)中国科学院物理研究所,表面物理国家重点实验室, 北京 100080; (2)中国科学院物理研究所,表面物理国家重点实验室, 北京 100080;吉林大学超硬材料国家重点实验室,长春 130012
Published: December 2020

The hydrogen-adsorbed diamond (001) surface is studied by ab initio pseudopotential method. The bare and monohydride surface configurations are calculated.The alteration of the charge density redistribution of the monohydride surface shows the formation of the C—H bonding, which leads to electron transfer from carbon atoms in the surface layer to the absorbed H atoms. The mechanism of alteration for charge density redistribution is discussed, which provides a theoretical background for the previous experimental observations and the model of electrical properties of diamond surface.
Study on piezoelectricity of hybrid films consisting of porous PTFE and Teflon FEP
Authors: Chen Gang-Jin  , Xia Zhong-Fu  ,   (1)同济大学波耳固体物理研究所，上海 200092; (2)浙江科技学院功能材料研究所，杭州 310012
Published: December 2020

The electret hybrid film consisting of porous PTFE and Teflon FEP is prepared through co-melting method at high temperature and with corona charging.Their piezoelectric responses are investigated by means of decay measurement of isothermal piezoelectric coefficient and charge density.The piezoelectric mechanism is discussed according to the theoretical model proposed by Kacprzyk et al.The results indicate that the piezoelectric responses not only result from charge density but also correlate to the charge distribution in the bulk of hybrid film.
The establishment and thermal stability of exchange bias in NiFe/FeMn bilayers
Authors: Teng Jiao  , Cai Jian-Wang  , Xiong Xiao-Tao  , Lai Wu-Yan  , Zhu Feng-Wu  ,   (1)北京科技大学材料物理与化学系,北京 100083; (2)北京科技大学材料物理与化学系,北京 100083;中国科学院物理研究所磁学国家重点实验室,北京 100080; (3)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

The establishment and thermal stability of exchange bias between the ferromagnetic NiFe layer and antiferromagnetic FeMn layer have been studied. We focused on the relationship between FeMn grain size and exchange bias with the size of FeMn grains controlled by varying Cr content in Ni-Fe-Cr alloy buffer layer. The results indicate that, smaller FeMn grains lead to a larger exchange bias field, but the thickness with the exchange bias setting on is larger, which is consistent with Mauri's model. Thermal stability of the exchange bias indicates that, the films with bigger FeMn grains have a higher blocking temperature, which is in agreement with Noshioka's conclusion: bigger antiferromagnetic grains possess higher activation energies and longer relaxation times.
Electrochromic effect of nanostructured WO3 bulk
Authors: Yang Xin-Sheng  , Wang Yu  , Dong Liang  , Zhang Feng  , Qi Li-Zhen  ,   华中科技大学物理系,武汉 430074
Published: December 2020

WO3 films are well known for the change of their color through electro, photo and thermochromism. We report here that the nanostructured WO3 bulk has an obvious electrochromic effect, which does not exist in ordinary WO3 bulk. The sample turns to a deep blue color upon changing from anode to cathode when external voltage is applied. There is no difference of the microstructure and phase structure between the colored and uncolored samples. X-ray photoelectron spectroscopy analysis shows that low valence state of tungsten ion (W5+) existed in the colored samples. Based on the experimental results, it is concluded that the coloration is an electron-injection effect. The high valence state of tungsten ion (W6+) in nanostructured WO3 bulk has enough activity to combine with electron and turns to the low valence state counterpart because of the surface effects of nanostructured materials. As a consequence, the sample changes its color.
The self-consistent theoretical study of the effect of surface plasmon and polariton on electronic transport
Authors: Miao Jiang-Ping  , Wu Zong-Han  , Sun Cheng-Xiu  , Sun Yue-Ming  ,   (1)东南大学电子工程系,南京 210096; (2)东南大学电子工程系,南京 210096东南大学物理系,南京 210096; (3)东南大学化工系,南京 210096; (4)东南大学物理系,南京 210096
Published: December 2020

The system charge density distribution was investigated by the self-consistent theory. Using the exciton theory, the frequency spectrum of surface plasmon and polariton(SPP) was derived by analyzing charge density matrix. Then, the electric transport matrix formed on the basis of atom orbit functions was classified into polynomial by the frequency spectrum of SPP. Moreover, the physics mechanism of negative resistance caused by the effect of SPP on electric transport was discussed.
Fabrication of pinned magnetic tunnel junctions using a contact shadow mask method
Authors: You Chen  , Zhao Yan-Ping  , Jin En-Ji  , Li Fei-Fei  , Wang Tian-Xing  , Zeng Zhong-Ming  , Peng Zi-Long  ,   (1)北京石油化工学院数理部，北京 102617; (2)天津理工学院材料科学与工程系，天津 300191; (3)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

Four types of pinned magnetic tunnel junctions (MTJs) with threekeylayer structures of Py/Al2O3/Py,Py/Al2O3/Co,Co/Al2O3/Py,Co/Al2O3/Co were fabricated using a contact shadow mask method and an antiferromagnetically pinned layer of Ir22Mn78.The slit width of the shadow mask is 100μm, and the composition of permalloy is Py＝Ni79Fe21.For example, the MTJs of Co/Al2O3/Co with a tunneling magnetoresistance (TMR) ratio of 17.2%, the junction resistance of 76?Ω, the resistance area product RS of 760?kΩμm2, and the freelayer reversal field of 1114A·m-1 defined as the field where the TMR rises to 50% of the total jump were achieved at the as deposited state at room temperature. Furthermore, when the magnetic field increases from 0 to 1114?A·m-1 the TMR ratio jumps from 0 to 17.2% with one step, which shows that the magnetic field sensitivity of the junction reached at 0.1%/(103A·m-1). While, the TMR vs external filed H curves for the pinned MTJs of Co/Al2O3/Py show a good rectangular shape with a small free-layer reversal filed of 1114?A·m-1. Our exprimental results show that such MTJs can be used to fabricate the magnetic field sensitive sensors or prototype demonstration devices of magnetoresistive random access memory.
Photoluminescence from a-Si:H/SiO2 multilayers fabricated using in situ layer by layer plasma oxidation
Authors: Ma Zhong-Yuan  , Huang Xin-Fan  , Zhu Da  , Li Wei  , Chen Kun-Ji  , Feng Duan  ,   南京大学固体微结构物理国家重点实验室，南京 210093
Published: December 2020

a-Si:H/SiO2 multilayers were layer by layer deposited and in situ plasma oxidized in a plasma-enhanced chemical vapor deposition system. Strong and stable blue photoluminescence at room temperature was observed from the as fabricated a-Si:H/SiO2 multilayers. By controlling the thickness of the a-Si:H sublayer from 4 to 1.5nm,the photoluminescence peak blueshifts from 465 to 435?nm. X-ray photo electron spectroscopy indicates that the oxide layer is of stoichiometric SiO2. Good passivation of a-Si:H/SiO2 interface is testified by C-V. Periodical structure and sharp a-Si:H/SiO2 interface is shown by transmission electron microscope. Combined with the measurements of absorption and photoluminescence, the origin of blue photoluminescence is attributed to the recombination of electrons and holes near the band-tail in a-Si:H sublayer under one-dimensional quantum confinement effect.
Study on lower-frequency voltage noise of moving vortex lattice in type-Ⅱsuperconductors
Authors: Zhao Zhi-Gang  , He Guo-Liang  , Wang Yong-Gang  , Liu Mei  ,   东南大学物理系，南京 210096
Published: December 2020

Using finite-temperature molecular dynamic simulations, we study the lower-frequency voltage noise in two-dimensional random-pinning-vortex lattices. We calculate the voltage noise spectrum of the vortex motion, and obtain the broadband noise (BBN) as a function of the driving current, pinning strength, and temperature. It is found that BBN increases with the pinning strength, and decreases with increasing temperature. These results are consistent with experiments and may be understood in terms of the microscopic dynamics of vortex motion.
The effect of impurity on the entanglement between the normal lattice in three-qubit Heisenberg XX chain
Authors: Zhang Tao  , Xi Xiao-Qiang  , Yue Rui-Hong  ,   (1)西安邮电学院应用数理系，西安 710061; (2)西北大学现代物理研究所，西安 710069
Published: December 2020

In this paper,we study the effect of impurity on the thermal entanglement between the normal lattice in three-qubit Heisenberg XX chain,and give the analytical expression of the concurrence.According to the discussion of our result,we find that the impurity parameter has a great effect on the pairwise thermal entanglement,it even can change the characters of the entanglement to some degree.