bluuebunny/crossref_metadata_2025 huggingface dataset:
Self-deflection of dark and gray photovoltaic solitons
Authors: Yan Li-Fen  , Wang Hong-Cheng  , Zhang Bing-Zhi  , She Wei-Long  ,   中山大学光电材料与技术国家重点实验室，广州 510275
Published: December 2020

We use both the numerical method and the perturbation technique to investigate the self-deflection process of a dark photovoltaic spatial soliton in a photovoltaic photorefractive crystal with diffusion effect. It is found that the dark soliton does not propagate along a parabolic trajectory, and it becomes grayer during the propagation in the photorefractive crystal. In the normalized coordinate system(ξ,ζ), the dark soliton deflects to the direction of ξ>0, which is different from that of the bright soliton. Besides, the deflection of dark solitons can be controlled effectively by modulating the ratio of effective Glass coefficient r and the intensity of the signal beam. We also investigated numerically the self-deflection characteristic of gray solitons, which depend on the direction of its initial transverse velocity v. When v>0, gray soliton deflects to the direction of ξ>0 in the coordinate system(ξ,ζ); when vξξ>0 after propagating for a small distance.
Photorefractive properties of Ca2+doped sodium barium niobate crystals
Authors: Gao Cheng-Yong  , Xia Hai-Rui  , Xu Jian-Qiang  , Si Shu-Chun  , Zhang Huai-Jin  , Wang Ji-Yang  , Song Hua-Long  ,   (1)山东大学晶体材料研究所,晶体材料国家重点实验室,济南 250100; (2)山东大学物理与微电子学院,济南 250100
Published: December 2020

The electronic mechanism of Ca2+ doped sodium barium niobate crystals and the change in induced photorefractive properties are studied based on its transmission properties. Curves of the refractive index changing with time are plotted using Michelson interferometry. Experimental results show that proper Ca2+doping in sodium barium niobate crystals can improve the photorefractive properties effectively.
High frequency message filtering characteristics of semiconductor laser as receiver in optical chaos communications
Authors: Wang Yun-Cai  , Li Yan-Li  , Wang An-Bang  , Wang Bing-Jie  , Zhang Geng-Wei  , Guo Ping  ,   太原理工大学物理系,太原 030024
Published: December 2020

The high frequency message filtering characteristics of the semiconductor laser which act as a receiver are numerically simulated in a scheme of closed-loop optical chaos communications system. Both transmitter and receiver are realized bysemiconductor lasers subject to strong optical injection. We examined the filtering properties of semiconductor laser with modulation message with different frequencies and amplitudes. The results demonstrate that the filtering effectiveness of the semiconductor laser receiver is higher for low frequency message and decreases as the message frequency approaches the relaxation oscillation frequency of the semiconductor laser. The quality of message recovery in such systems is shown to depend not only on the synchronization quality but also on the difference in amplitude of the message in the transmitter and receiver outputs.
Experimental study of flow characteristics in rough microchannels
Authors: Hao Peng-Fei  , Yao Zhao-Hui  , He Feng  ,   清华大学工程力学系,北京 100084
Published: December 2020

The effect of surface roughness on the frictional characteristics of the liquid flow in the microchannels with distributed rectangular roughness elements is experimentally studied. The velocity fields are obtained by micro particle image velocimetry (micro-PIV). The friction coefficients in the microchannels with 3%—7% relative roughness are higher than the prediction based on the conventional theory due to the additional pressure drag caused by roughness elements. The existence of roughness elements gives rise to additional disturbance in the laminar stream, and the early transition to turbulent flow in the rough microchannels is validated.
Stimulated trapped electron-acoustic wave scattering and ion-vortices in subcritical plasmas
Authors: Li Bai-Wen  , Tian En-Ke  ,   (1)北京应用物理与计算数学研究所,北京 100088; (2)中国地质大学材料科学与工程学院，北京 100083
Published: December 2020

Stimulated trapped electron-acoustic wave scattering instability by a linearly-polarized laser interacting with a plasma layer at a subcritical density range is studied by particle simulation. Its early behavior is almost the same whether ion dynamics is taken into account or not. However, when ion dynamics is considered, a large ion acoustic wave is excited, which grows with time and eventually breaks up locally, followed by the generation of a large amplitude electromagnetic soliton. As a new phenomenon, an ion-vortex structure in ion phase-space is formed due to the ion acceleration and trapping by high local electromagnetic and electrostatic fields inside the soliton. As the electromagnetic soliton is accelerated backwards, several ion-vortices are formed in the wake behind. Ion-vortices are also found in inhomogeneous subcritical plasmas. These ion-vortices are recognized as the Kelvin-Helmholtz instability patterns, likely to be formed due to a topological defect, i.e., the plasma density cavity in the electromagnetic soliton region, which exhibit the well-known paradigmatic Ying-Yang pattern.
Experimental study of injection depth and fuelling effects during supersonic molecular beam injection on the HL-2A tokamak
Authors: Shi Zhong-Bing  , Yao Liang-Hua  , Ding Xuan-Tong  , Duan Xu-Ru  , Feng Bei-Bin  , Liu Ze-Tian  , Xiao Wei-Wen  , Sun Hong-Juan  , Li Xu  , Li Wei  , Chen Cheng-Yuan  , Jiao Yi-Ming  ,   核工业西南物理研究院，成都 610041
Published: December 2020

The fuelling efficiency and injection depth are the fundamental problems of supersonic molecular beam fuelling. In the recent supersonic molecular beam injection (SMBI) experiments, the injection depths of SMBI have been found mainly dependent on the background electron density and temperature, the source gas pressure and temperature. The empirical scaling of SMBI depth was obtained at room temperature. Hydrogen clusters formed in the beam have been observed in the low temperature (source gas at liquid nitrogen temperature) SMBI experiments. It resulted in injection depth greater than 30 cm. Comparing the relationships between injection depths, plasma background parameters and molecular source temperature, the cluster formation phenomena during low temperature MBI are analyzed.
Equation of state of detonation products based on statistical mechanical theory
Authors: Zhao Yan-Hong  , Liu Hai-Feng  , Zhang Gong-Mu  ,   北京应用物理与计算数学研究所，北京 100088
Published: December 2020

The equation of state of gas detonation products is described by Ross's modification of hard-sphere variation theory and the improved one-fluid van der Waalsmixture model. The Gibbs free energy of dissociated carbon is calculated for the most probable state, which is determined by differentiating the four states of carbon, namely graphite, diamond, graphitelike and diamondlike. The equilibrium composition of detonation products are calculated by solving chemical equilibrium equations based on minimizing Gibbs free energy. The results are in good agreement with the results based on Becker-Kistiakowsky-Wilson (BKW) and Lennard-Jones-Devonshire equations of state. The detonation properties of explosives are calculated with this theory. The results of high density explosives based on BKW, Jones-Wilkins-Lee (JWL) and our equations of state are in good agreement with the experimental data. For low density explosives our results are better than that of BKW and JWL.
The effect of impurities on the Young’s modulus of single-walled carbon nanotubes
Authors: Yuan Jian-Hui  , Cheng Yu-Min  ,   (1)上海大学上海市应用数学和力学研究所,上海 200072; (2)上海大学上海市应用数学和力学研究所,上海 200072;长沙理工大学物理与电子科学学院,长沙 410076
Published: December 2020

The molecular dynamics method was used to investigate the effect of the impurities N,O,Si,P and S on the Young's moduli of armchair (5, 5) and zigzag (9, 0) single-walled carbon nanotubes. The results show that the Young's moduli of armchair (5, 5) and zigzag (9, 0) single-walled carbon nanotubes are 948 and 804 GPa, respectively. When the impurity concentration is less than 10%, the Young's moduli are approximately linearly decreasing with increasing of the impurity concentration, and the greatest decreasing ratio is induced by the impurity Si and the smallest by the impurity N. The decreasing rate of the Young's modulus increases with increase of the impurity atomic number when the impurity element is of the same period with the element C. The effect of the impurities on the Young's modulus of carbon nanotubes is the stronger when the period of the impurity element is different with the element C, and the decreasing rate of the Young's modulus decreases slightly with increasing of the impurity atomic number. The reasons are analyzed by the laws of the Young's potential energy variation of carbon nanotubes with impure and the electron cloud coupling between two atoms from the theory of the local density approximation based on the density functional theory.
Preparation of p-type ZnO thin films by in situ oxidation of Zn3N2
Authors: Zhang Jun  , Xie Er-Qing  , Fu Yu-Jun  , Li Hui  , Shao Le-Xi  ,   (1)兰州大学物理科学与技术学院，兰州 730000; (2)兰州大学物理科学与技术学院，兰州 730000;湛江师范学院物理科学与技术学院，湛江 524048; (3)湛江师范学院物理科学与技术学院，湛江 524048
Published: December 2020

Low resistance p-type ZnO thin films were prepared by in situ oxidation of Zn3N2 films which were deposited by reactive radio-frequency magnetron sputtering of zinc in Ar-N2 mixture atmosphere. The effects of oxidation temperature and time on structural, electronic and optical properties of the samples were investigated by X-ray diffraction, scanning electron microscopy, Hall-effect measurements, transmittance spectra and photoluminescence spectra. It was found that the sample oxidized at 450 ℃ contains Zn2N3 besides ZnO. The sample oxidized at 500 ℃ for 2 h had good properties of low resistance (0.7 Ωcm), good transmittance rate (above 85%)，predominant excitonic ultraviolet emission with narrow full width at half maximum and weak deep level visible emission. The low resistance p-type ZnO films could be used in short wavelength industrial application.
The influence of spin relaxation on the entanglement of photon pairs emitted from degenerate exciton quantum dot system
Authors: Liu Shao-Ding  , Cheng Mu-Tian  , Wang Xia  , Wang Qu-Quan  ,   (1)武汉大学物理系，武汉 430072; (2)武汉大学物理系，武汉 430072;武汉大学声光材料与器件教育部重点实验室，武汉 430072
Published: December 2020

The second-order cross correlation function of the photon emission and the polarization density matrix of the photon pairs emitted from the biexciton system of single semiconductor quantum dots under pulsed excitation were calculated using the dynamical population density matrix equations and quantum regression theorem. The entanglement of the photon pairs emitted from the single quantum dot with degenerate exciton states were investigated, and the relationship between the entanglement and the spin relaxation rate was also discussed. The simulations revealed that the spin relaxation destroys the entanglement of the photon pairs emitted from this system.
Electrical and optical properties of InAs/GaAs quantum dots doped by high energy Mn implantation
Authors: Hu Liang-Jun  , Chen Yong-Hai  , Ye Xiao-Ling  , Wang Zhan-Guo  ,   中国科学院半导体研究所，北京 100083
Published: December 2020

V+ were implanted into anantase films by metal ion implantation. The electronic band structures of TiO2 films doped with V+ were calculated using a self-consistent full-potential linearized augmented plane-wave method with
Subband electron properties of InGaAs/InAlAs high-electron-mobility transistors with different channel chickness
Authors: Gao Hong-Ling  , Li Dong-Lin  , Zhou Wen-Zheng  , Shang Li-Yan  , Wang Bao-Qiang  , Zhu Zhan-Ping  , Zeng Yi-Ping  ,   (1)中国科学院半导体研究所，北京 100083; (2)中国科学院上海技术物理研究所红外物理国家重点实验室，上海 200083
Published: December 2020

Magnetotransport properties of In0.53GaAs/In0.52AlAs high electron mobility transistor (HEMT) structures with different channel thickness of 10—35 nm have been investigated in magnetic fields up to 13 T at 1.4 K. Fast Fourier transform has been employed to obtain the subband density and mobility of the two-dimensional electron gas in these HEMT structures. We found that the thickness of channel does not significantly enhance the electron density of the two-dimensional electron gas, however, it has strong effect on the proportion of electrons inhabited in different subbands. When the size of channel is 20 nm, the number of electrons occupying the excited subband, which have higher mobility, reaches the maximum. The experimental values obtained in this work are useful for the design and optimization of InGaAs/InAlAs HEMT devices.
Structure and superconductivity of the ternary silicide CaAlSi
Authors: Ma Rong  , Huang Gui-Qin  , Liu Mei  ,   (1)东南大学物理系，南京 210096; (2)南京师范大学物理系，南京 210097
Published: December 2020

V+ were implanted into anantase films by metal ion implantation. The electronic band structures of TiO2 films doped with V+ were calculated using a self-consistent full-potential linearized augmented plane-wave method with
Spectroscopic properties of Er3+and Er3+/Yb3+ co-doped bismuth glasses
Authors: Jia Xiang-Hua  , Lü Shu-Chen  ,   哈尔滨师范大学物理系，哈尔滨 150025
Published: December 2020

The Er3+ and Er3+/Yb3+ co-doped bismuth glasses were prepared in this work. The absorption spectra and fluorescence spectra of the glasses were measured at room temperature. The strength parameters calculated according to the Judd-Ofelt theory from the absorption spectra are Ω2=(5.47—2.92)×10-20 cm2，Ω4=(2.16—1.22)×10-20 cm2, and Ω6=(1.29—0.80)×10-20 cm2. The absorption cross section at 980 nm and intensty of emission spectra at 1.5 μm were compared. FWHM of the broad fluorescence band of Er3+/Yb3+ co-doped bismuth glass at 1.5 μm is 91 nm, which is 15 nm larger than that of Er3+-doped bismuth glass. Emission cross section of σe=1.00×10-20 cm2 has been obtained using McCumber theory. The optical properties of Er3+ ion in bismuth-based glass are discussed by comparing with other glasses. The results show that Er3+ dopingof bismuth based glass is highly preferable for optical amplifier to realize broadband high gain amplification.
Autowave-competition neural network and its application to the single-source shortest-paths problem
Authors: Dong Ji-Yang  , Zhang Jun-Ying  , Chen Zhong  ,   (1)西安电子科技大学雷达信号处理国家重点实验室，西安 710071; (2)厦门大学物理系，福建省半导体照明工程技术研究中心，厦门 361005; (3)厦门大学物理系，福建省半导体照明工程技术研究中心，厦门 361005;西安电子科技大学雷达信号处理国家重点实验室，西安 710071
Published: December 2020

In this paper, the competitive mechanism is introduced to the production and propagation processes of the autowave of neural network. The autowave-competition neural network (ACNN) is proposed to successfully resolve the problem of single-source shortest paths (SSSP). The algorithm for shortest paths based on ACNN is presented. Compared with other neural network based approaches, the new algorithm has the following advantages: less number of neurons needed, simple structure of neurons and networks, readily available software and hardware. When ACNN is employed to resolve the shortest path problem, the computational complexity is only related to the hop number of the shortest path, but independent of the complexity of path graph, the number of the existing paths in the graph and the precision of the length of edges. Simulations show that the proposed algorithm is plausible and effictive.
The strict solutions to the field distribution of superconducting unbounded slab model
Authors: Yang Peng-Fei  , Bai Jin-Tao  , Yang Xiao-Peng  ,   (1)西北大学光子学与光子技术研究所，西安 710069; (2)西北大学光子学与光子技术研究所，西安 710069;陕西广播电视大学榆林市分校，榆林 719000; (3)榆林市工业学校，榆林 719000
Published: December 2020

The strict solutions of superconducting unbounded slab model are given for its field distribution, the validity of approximate results avceilable from literature is verified.
The analytic solution of the radial Schr?dinger equation for the superposed potential of high-order power and inverse-power potential functions
Authors: Hu Xian-Quan  , Xu Jie  , Ma Yong  , Yin Lin  ,   重庆师范大学物理学与信息技术学院, 重庆 400047
Published: December 2020

When the Schrdinger equation involves high-order power and inverse power potential functions or the superposed potential function of high-order anharmonic oscillatory potentials, introduced by the presence of electric dipole moment potential, molecular crystal potential, or the polarized equivalent potential, the solution of the Schrdinger equation becomes very complicated. In this paper, with the help of a combination of series solutions and asymptotic solutions utilized near the singular points, a series analytic solution of the wave functions of stationary state for radial Schrdinger equation with potential function V(r)=a1r6+a2r2+a3r-4+a4r-6 and the corresponding energy level structure are obtained under the tightly-coupled condition of the interacting power potential functions. Meanwhile, the paper gives a proper discussion and some important conclusions are drawn.
Nonlinear Rosen-Zener transition
Authors: Ye Di-Fa  , 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)厦门大学物理系,厦门 361005; (3)中国工程物理研究院北京研究生部,北京 100088;北京应用物理与计算数学研究所,北京 100088;厦门大学物理系,厦门 361005
Published: December 2020

We investigate the nonlinear Rosen-Zener transition in two-mode systems. A non-trivial collective behavior, in which all the atoms tend to stay at only one of the modes, emerges with the appearance of nonlinear interaction under the adiabatic approximation. The application of an external field can transfer the atoms from one mode to the other completely. Such phenomena can be fully understood with the help of the phase diagram. We expect the predicted effect will be detected in current BEC experiments.
Instantaneous radiant emittance of the accelerating non-stationary black hole
Authors: Meng Qing-Miao  , Su Jiu-Qing  , Jiang Ji-Jian  ,   菏泽学院物理系,菏泽 274015
Published: December 2020

Using entropy density near event horizon of the accelerating non-stationary black hole, the instantaneous radiant emittance is calculated, and we arrive at the conclusion that the instantaneous radiant emittance of black hole in a direction at any time is always proportional to the quartic power of temperature of the event horizon of black hole in that direction. It is found that the generalized Stefan-Boltzmann coefficient is no longer a constant, but a coefficient dynamically related to the rate of change of event horizon, the structure of space-time near event horizon and the radiation absorption coefficient of the black hole. It shows that an intrinsic relation between the gravitational field around the black hole and its thermal radiation must exist.
The mean first-passage time for an asymmetric bistable system driven by multiplicative colored and additive white noise with a correlated noise
Authors: Zhang Na-Min  , Xu Wei  , Wang Chao-Qing  ,   西北工业大学应用数学系,西安 710072
Published: December 2020

We investigated the effects of asymmetry of the potential and noises on the mean first-passage time (MFPT) in two opposite directions in an asymmetric bistable system subjected to multiplicative colored and additive white noise with a correlated noise. The expression of the stationary probability distribution is obtained by means of an extended unified colored-noise approximation and the expressions of the MFPTs are derived through the steepest-descent approach. Numerical results show that the influence of the asymmetry coefficient r on T± is different and because of the correlated noise，even for r=0, T+(xs1→xs2,r) is not equal to T-(xs2→xs1,r). The curves of　lnT± versus r in both cases have mono-valleys but the mono-valleys move to the opposite directions with increasing correlation intensity λ.
Stochastic resonance of amplitude modulation wave in single-mode laser driven by color noises
Authors: Zhang Liang-Ying  , Cao Li  , Jin Guo-Xiang  ,   (1)华中科技大学激光技术国家重点实验室,武汉 430074; (2)武汉工程大学计算机学院，武汉 430073; (3)襄樊学院物理系，襄樊 441053
Published: December 2020

By adding modulation wave to the equation of the laser intensity in the gain-noise model of the single-mode laser, we use the linear approximation method to calculate the power spectrum and signal-to-noise ratio(SNR) of the laser intensity, which is driven by two color noises correlated in the form of exponential function. The result shows that the correlated time and the correlated strength between the noises have great effect on the stochastic resonance(SR), and the variations of SNR with the frequency of the carrier signal ω and the modulator signal Ω are quite different from the curve of variation of white noise.
Four-dimensional switchable hyperchaotic system
Authors: Liu Yang-Zheng  , Jiang  Chang-Sheng  , Lin  Chang-Sheng  , Sun Han  ,   (1)南京工程学院非线性物理研究所,南京 211167; (2)南京工程学院非线性物理研究所,南京 211167;南京航空航天大学自动化学院,南京  210016; (3)南京航空航天大学自动化学院,南京  210016
Published: December 2020

A class of four-dimensional switchable hyperchaotic systems is built by adding an additional state to the three-dimensional switchable chaotic system. When subsystems are hyperchaotic, an identical system parameter is determined according to the bifurcation diagrams of the subsystems. Some of its basic dynamical properties are studied detailedly, such as the feature of equilibrium, the phase portraits of hyperchaotic attractor,the Lyapunov exponent and the fractal dimension. A practical circuit is designed to realize these systems.
The characteristic analysis of the traffic flow of trains in speed-limited section for fixed-block system
Authors: Fu Yin-Ping  , Gao Zi-You  , Li Ke-Ping  ,   北京交通大学轨道交通控制与安全国家重点实验室，北京 100044
Published: December 2020

For speed-limited sections of railway traffic in the four-aspect fixed-block system, we propose a cellular automata model to simulate the traffic flow to analyze how the length of speed-limited section, train time interval and the speed-limit value affect the traffic flow. The simulation results demonstrate that the decrease of the length of speed-limited section, the moderate increase of train time interval and the increase of the speed-limit value can improve the green light runtime of the trains.
Effective polymerization of C60 in SWNTs under high pressure and simultaneous UV light irradiation
Authors: Zou Yong-Gang  , Liu Bing-Bing  , Yao Ming-Guang  , Hou Yuan-Yuan  , Wang Lin  , Yu Shi-Dan  , Wang Peng  , Cui Tian  , Zou Guang-Tian  , Sundqvist B.  , Wang Guo-Rui  , Liu Yi-Chun  ,   (1)东北师范大学物理学院,长春 130024; (2)吉林大学超硬材料国家重点实验室,长春 130012; (3)瑞典Ume大学物理系,S-90187
Published: December 2020

The C60@SWNT (peapod) samples were prepared by the vapor diffusion method. Polymerization of C60 molecules in single walled carbon nanotubes (SWNTs) under high pressure and simultaneous irradiation of UV laser (325 nm) has been carried out for the first time by using diamond anvil cell. Raman spectra of the peapod samples decompressed from high pressure indicated that C60 molecules form one-dimensional orthorhombic polymer in SWNTs under UV laser irradiation at a high pressure of 21.5GPa, which is lower than that for the polymerization of samples induced by high pressure only. The polymerization is an irreversible phase transition in the peapod.
A theoretical study on (e, 2e) process for helium in large energy loss and close to minimum momentum transfer geometry
Authors: Yang Huan  , Gao Kuang  , Zhang Sui-Meng  ,   (1)安徽师范大学物理与电子信息学院,芜湖 241000; (2)安徽师范大学物理与电子信息学院,芜湖 241000;安徽皖西学院数理系原子与分子物理研究所,六安 237012
Published: December 2020

The triple differential cross section for electron impact ionization of helium in the special geometry of coplanar large energy loss and close to minimum momentum transfer are calculated by use of BBK model and modified BBK model. The structure of the cross section is discussed.The results of the present work are compared with current experimental data. It is found that both BBK and modified BBK models are in good agreement with the experimental results of binary-to-recoil peak ratio and their angular distribution.
Ground-state structures and stabilities of Zrn(n=2—16) clusters studied with density-functional theory
Authors: Zhao Wen-Jie  , Lei Xue-Ling  , Yan Yu-Li  , Yang Zhi  , Luo You-Hua  ,   (1)河南大学物理与电子学院,开封 475004; (2)河南大学物理与电子学院,开封 475004;华东理工大学理学院,上海 200237
Published: December 2020

The geometries，total energies，and frequencies of Zrn(n=2—16) clusters have been systematically investigated by using density functional theory with the generalized gradient approximation.Ｔhe equilibrium geometries for different spin multiplicities as well as the ground-state structures have been determined.The calculated results on the averaged binding energy， fragmentation energy， second-order difference of cluster energies as well as the HOMO-LUMO gap of the Zrn(n=2—16) clusters indicate that the relative stabilities ofZr2，Zr5，Zr7，Zr13，Zr15 are stronger than clusters of othersizes. The true ground state for Zr13 cluster has icosahedral structure with Ih symmetry，and the stability of Zr13 is the strongest of all the investigated clusters.
Stable quantum key distribution with polarization control
Authors: Chen Jie  , Li Yao  , Wu Guang  , Zeng He-Ping  ,   华东师范大学光谱学与波谱学教育部重点实验室, 上海 200062
Published: December 2020

In this paper, we promote a principle of polarization feedback which keeps polarization states stable in long-distance fiber. It is quite difficult to realize long-term stable quantum key distribution (QKD) with polarization encoding due to the effect of irregular polarization fluctuation in single mode fiber. We have designed a polarization feedback control system to compensate for the birefringence. And a polarization encoded QKD experiment has been realized in 100km fiber.
Reverse saturable absorption of porphyrin-like complexes
Authors: Zhang　Bing  , Liu Zhi-Bo  , Chen Shu-Qi  , Zhou Wen-Yuan  , Zang Wei-Ping  , Tian Jian-Guo  , Luo Dai-Bing  , Zhu Zhi-Ang  ,   (1)南开大学化学学院，天津 300071; (2)南开大学泰达应用物理学院弱光非线性光子学材料先进技术及制备教育部重点实验室，天津 300457
Published: December 2020

We report here the experimental observations on the nature of the reverse saturable absorption over the visible region(450—470 nm) for two novel porphyrin-like complexes and tetraphenylporphyrin using open aperture z-scan. They all exist large reverse saturable absorption between the Soret and Q bands. A theoretical study has been carried out using 5-level models. The two novel samples have better optical limiting than tetraphenylporphyrin.
Influence of matrices on electron temperature of laser micro-plasma in argon atmosphere at reduced pressure
Authors: Guo Qing-Lin  , Zhou Yu-Long  , Zhang Bo  , Zhang Qiu-Lin  , Zhang Jin-Ping  , Huai Su-Fang  ,   河北大学物理科学与技术学院，保定 071002
Published: December 2020

Laser micro-spectral analysis coupled with CCD spectrometer was used in this experiment. With Fe Ⅰ356.54 nm and Fe Ⅰ358.12 nm as analysis spectral lines, the micro-plasma temperature and its spatial distribution were investigated in different matrices, namely Mg, Al, Si, and steel alloy 6-0. The electron temperature as a function of location in each matrix and the differences of that at the same location in different matrices were determined and an explanation was given. Finally, with Cu Ⅰ324.75 nm and Zn Ⅰ394.50 nm as analysis spectral lines, we have successfully used the calculated micro-plasma temperature to discuss the matrix effect.
Two-electron InAs quantum-dot-molecular qubit modulated by the orientation of magnetic fields
Authors: Dong Qing-Rui  ,   山东师范大学物理与电子科学学院，济南 250014
Published: December 2020

The electronic structure of a two-electron quantum-dot molecular has studied using the effective mass approximation. The quantum-dot molecular consists of two vertically coupled self-assembled quantum disks in a magnetic field with varying orientation. Based on the calculation, a qubit modulated by the orientation of magnetic field is proposed with the total spin of the system. Electron correlations may lead to the switching of the total spin between S=0 and S=1 states. The switching is realized not by the changing strength but by the changing orientation of an external magnetic field. Our results provide a possibility to use the total spin of the system as a qubit modulated by varying the orientation of the magnetic field. Since high-quality vertically stacked quantum disks can be fabricated successfully, it is realistic to obtain qubits of this type.
Analytical model of charge transport at organic semiconductor interfaces
Authors: Li Xun-Shuan  , Peng Ying-Quan  , Yang Qing-Sen  , Xing Hong-Wei  , Lu Fei-Ping  ,   兰州大学物理科学与技术学院，兰州 730000
Published: December 2020

The performances of organic semiconductor thin film devices are largely determined by the transport properties of the organic-organic (OO) interfaces，but many present theories concerning charge transport at OO interfaces are not suitable for practical device modelling. Based on the Miller-Abrahams formalism for hopping conduction, an analytical model for charge transport at OO interfaces has been developed by considering the difference between OO interfaces and metal-organic interfaces. The result shows that the transport of carriers at an OO interface depends not only on the energy barrier of the interface, but also on the carrier concentration and the electric field at the two sides of the interface. This model can be used to self-consistent calculations of the current density, field distribution and other characteristics in multiplayer organic semiconductor devices.
Spontaneous magnetization in superconducting π ring and 0 ring mixed arrays
Authors: Ma Xiao-Bai  , Dai Yuan-Dong  , Wang Fu-Ren  , Hu Qi  , Nie Rui-Juan  ,   北京大学物理学院，人工微结构和介观物理国家重点实验室，北京 100871
Published: December 2020

Regular mixed arrays of superconducting π rings and 0 rings have been investigated. Our calculation shows that the free energy of inverse spontaneous magnetization of two π rings indirectly coupled via a 0 ring is lower. The state of the full antiparallel pattern of π rings is favorable in the regular mixed arrays. This is a quantum phase coherence result of superconducting wave functions.
Upconversion luminescence in Yb3+ sensitized Er3+/Yb3+-codoped tellurite glasses
Authors: Dai Shi-Xun  , Li Xu-Jie  , Nie Qiu-Hua  , Xu Tie-Feng  , Shen Xiang  , Wang Xun-Si  ,   宁波大学信息科学与工程学院，宁波 315211
Published: December 2020

A series of Er3+/Yb3+-codoped，Ho3+/Yb3+-codoped，and Er3+/Yb3+/Ho3+-triply doped tellurite glasses were prepared by high-temperature melting. Under 975nm laser light excitation，intense green and red upconversion luminescence was observed in all the three kinds of codoped tellurite glasses. The influence of Yb3+ ions on the upconversion emission properties of Er3+ and Ho3+ ions was investigated as well as the energy transfer efficiencies of Yb3+→Er3+ and Yb3+→Ho3+. Upconversion luminescence mechanisms of Er3+ and Ho3+ sensitized by Yb3+ in tellurite glasses were discussed. When the concentrations of Er3+ and Ho3+ ions were fixed at low values，the intensity of green and red upcoversion emission in Er3+/Yb3+/Ho3+-triply doped tellurite glasses increases with increasing Yb2O3 content, which are due to the interaction overlap of Er3+：4S3/2→4I15/2 and Ho3+：5S2(5F4)→5I8 transitions，Er3+：4F9/2→4I15/2 and Ho3+：5F5→5I8 transitions，respectively. In Er3+/Yb3+/Ho3+-triply doped tellurite glasses，the upconversion luminescence mechanisms were affected by the interaction energy transfers of Er3+/Yb3+, Ho3+/Yb3+ and Er3+/Ho3+. The cross-relaxation between Er3+ and Ho3+ enhances the upconversion emission intensities of Ho3+ in the visible region.
The electroluminescence spectra of dual wavelength GaN-based light emitting diodes
Authors: Gu Xiao-Ling  , Guo Xia  , Liang Ting  , Lin Qiao-Ming  , Guo Jing  , Wu Di  , Xu Li-Hua  , Shen Guang-Di  ,   北京工业大学北京市光电子技术实验室，北京 100022
Published: December 2020

GaN-based dual-wavelength light emitting diodes (LEDs) with different In contents in the wells and barriers was designed and fabrieated in our experiment. Electroluminescence of the fabricated LED at the typical driving current of 20mA has two colors，blue and green respectively. The ratio of the intensities of the green light to the blue light increases with increasing driving current. At larger current，the blue shift of the peak wavelength of the green light was greater than that of the blue light. We are also concerned with the effect of polarization and non-uniform carrier distribution in the active region. Using coupled method of simulation，the calculated data were consistent with the experiment.
Multiphase field simulation of the eutectic growth under three schemes of varying velocity
Authors: Zhu Yao-Chan  , Wang Jin-Cheng  , Yang Gen-Cang  , Yang Yu-Juan  ,   西北工业大学凝固技术国家重点实验室，西安 710072
Published: December 2020

By multiphase field model method，the unidirectional solidification of eutectic alloy CBr4-C2Cl6 is simulated，and the adjustment of lamellar spacing and morphology evolution have been investigated under three schemes of variable pulling speed，i.e., the stepped change，the linear change and the oscillatory change. The simulation results show that，for the growth under these three schemes，both the interface average velocity and the interface average undercooling show hysteresis effect. When the stepped increase or decrease in velocity is imposed，the lamellar spacing adjustment is realized through abrupt branching or progressive merging and annihilation accompanying the lamellar growing，respectively，and there is strong asymmetry in these two processes during lamellar adjustment. In the case of linear increase in velocity，the lamellar spacing changes by progressive branching，while in the case of linear decrease in velocity，the mechanism of adjustment of lamellar spacing is similar to that of growth under stepped decrease of velocity. The processes for linear increase and decrease in velocity show inverse symmetrical characteristic. A quasi-1λ oscillation mode is present when an oscillatory pulling speed is applied.
Measurement and analysis of direct sunlight and skylight spectra
Authors: Cao Ting-Ting  , Luo Shi-Rong  , Zhao Xiao-Yan  , Liang Hui-Min  , Wang Hong-Bo  , Yang Jing-Guo  ,   四川大学物理系，成都 610064
Published: December 2020

The extraterrestrial spectrum in the visible wavelength range of 340.5—818.6nm at the height of 9.6 km has been detected，furthermore，the upper sunlightand skylight spectra have been collected in different regions of Chengdu and Lijiang. The date and diagram indicated that 482.1nm is the hightest point in extraterrestrial direct solar spectra, and that of the extraterrestrial skylight spectra is shifted to 412nm. The skylight spectra registered on sunny and cloudy days are notably different. It was also found that the firn on top the Yulong Mountain has different albedos in different wavebands visible range.
Mesoscopic impedivity of Fe-based nanocrystalline alloy and its application
Authors: Yang Quan-Min  , Xu Qi-Ming  , Yang Yi  , Fang Yun-Zhang  ,   (1)华中科技大学文华学院电子与信息工程系，武汉  430074; (2)西安建筑科技大学材料科学与工程学院,西安  710055; (3)西安建筑科技大学材料科学与工程学院,西安  710055；连云港师范高等专科学校物理系,连云港  222006
Published: December 2020

We put forward an physical concep for the mesoscopic impedivity of Fe-based nanocrystalline alloy for the first time, and its formula ρ=-μ{A}/{t}/Δ×His obtained by using Maxwell system of equations. The formula shows that the mesoscopic impedivity ρ of Fe-based nanocrystalline alloy depends on the mesoscopic magnetic field intensity H, mesoscopic magnetic vector potential A, and mesoscopic permeability μ. The mesoscopic magnetic vector potential A is caused by the effect of quantum mechanics with the mesoscopic structure in the studied material, and is determined by the microcosmic structure of the studied material. Magneto-resonance frequency shift of nanocrystalline Fe735Cu1Nb3Si135B9 powder for its giant magneto-impedance(GMI) effect and frequency resonance magnetic field intensity shift of nanocrystalline Fe730Cu10Nb15V20Si135B90 microwire with the multilayer structure for its GMI effect are explained successfully by the formula.
Relaxation resulting from atomic defects in quenched Fe-Al alloys
Authors: Zhou Zheng-Cun  , Zhao Hong-Ping  , Gu Su-Yi  , Wu Qian  ,   苏州市职业大学，苏州  215104
Published: December 2020

Two relaxational internal friction peaks in quenched Fe-Al alloys with different Al content have been investigated using a computer-controlled automatic inverted torsion pendulum through free-decay and forced vibration method. It has been shown that the two peaks (P1, 180℃ and P2, 340℃) appear only in the heating process and do not appear in subsequent in-situ cooling process. It is suggested that P1 resulted from the stress-induced reorientation of di-vacancies, which consists of the reorientation of nearest neighbour Fe-vacancies on the α and　β (or　γ) sublattice sites. The relaxation strength of P1 varies im-monotonicly with Al content and there is a maximum at about 25% Al(atomic percent). There is no P1 peak in the Fe-Al alloys with lower Al content since vacancies exist in the form of isolated vacancies. When Al content is over 25%, the number of vacancies on β and　γ sites is reduced. Therefore, the nearest neighbour di-vacancies are decreased and the height of P1 peak declines. P2 originates from the stress-induced reorientation of FeAl-VFe dipoles under. P2 does not appear in the Fe-Al alloys with Al less than 22% since no FeAl anti-site atoms and FeAl-VFe dipoles are produced.
First-principles calculations on the electrical structures and vibration frequencies of β-Si3N4
Authors: Zhu Ying-Tao  , Yang Chuan-Lu  , Wang Mei-Shan  , Dong Yong-Mian  ,   鲁东大学物理与电子工程学院，烟台  264025
Published: December 2020

Both unit cell parameters and fractional atomic coordinates of β-Si3N4 have been fully relaxed using Crysta106 program that adopts all-electron gauss-type basis sets and the density functional theory (PW91 and B3LYP). The geometrically optimized results are in excellent agreement with experiment. The band structure and density of states are also calculated. Based on the optimized geometries, the vibration frequencies have been calculated at Γ point using PW91 and B3LYP method with symmetry assignment. The 11 Raman mode frequencies are compared with experiment and other theoretical results, and the missing Ag mode frequency is assigned to 459cm-1. The present calculation shows that the results of B3LYP are better than those of PW91 In the intermediate and low-frequency region, the largest differences from experimental results are 2 and 17cm-1, while in the high-frequency region the largest differences are 16　and 35cm-1 respectively. For IR frequencies, the symmetries of the experimental data are assigned by comparing them with the present theoretical results.
Phase-field model of isothermal solidification of binary alloy with multiple grains
Authors: Feng Li  , Wang Zhi-Ping  , Lu Yang  , Zhu Chang-Sheng  ,   (1)兰州理工大学材料科学与工程学院,兰州  730050; (2)兰州理工大学材料科学与工程学院,兰州  730050；甘肃省有色金属及复合材料工程技术研究中心,兰州  730050
Published: December 2020

A new phase-field model for dendrite growth of multiple grains is developed based on the Ginzberg-Landau theory and phase-field model of single grains. Taking Al-2mole-Cu alloy for example, in connection with the concentration field, we simulated the dendritic growth process of multiple grains during isothermal solidification. The simulation showed dendritic competitive growth of multiple grains, and reproduced the process of dendrite growth in practical solidification.
Photo-thermal ionization spectroscopy of shallow acceptors in high purity germanium
Authors: Yu Chen-Hui  , Zhang Bo  , Yu Li-Bo  , Li Ya-Jun  , Lu Wei  , Shen Xue-Chu  ,   (1)西南技术物理研究所，光电器件部，成都  610041; (2)中国科学院上海技术物理研究所，红外物理国家重点实验室，上海  200083; (3)中国科学院上海技术物理研究所，红外物理国家重点实验室，上海  200083；西南技术物理研究所，光电器件部，成都  610041
Published: December 2020

The results of high sensitivity photo-thermal ionization spectroscoic (PTIS) investigation of shallow acceptors in high purity p-type germanium sample with room temperature resistivity of about 50Ω·cm, at temperature above liquid helium by Fourier transform spectrometer and associated magneto-optical measurement systems, are reported. The optimum photo-thermal ionization temperature range for the shallow impurities in high purity germanium is determined experimentally. At temperatures within this range, the PTIS spectra of this sample were measured. Boron and aluminum are found to be the main shallow acceptors in the sample. The causes of line splits of spectra, rapid recombination of compensating impurity and random strain, are analyzed and discussed.
New exact solutions and special soliton structures for the (3+1)-dimensional Burgers system
Authors: Ma Song-Hua  , Wu Xiao-Hong  , Fang Jian-Ping  , Zheng Chun-Long  ,   浙江丽水学院物理系，丽水  323000
Published: December 2020

Applying the improved mapping approach and variable separation method to the (3+1)-dimensional Burgers system，the new exact solutions of the system is derived. Based on the derived solitary wave solution，we obtained some special soliton structures，such as cylinder-like soliton，tapered soliton and embeded-solitons，and the interactions between the solitons are discuessed.
Compensating impurity in high purity silicon single crystal investigated by photo-thermal ionization spectroscopy
Authors: Yu Chen-Hui  , Zhang Bo  , Yu Li-Bo  , Li Ya-Jun  , Lu Wei  , Shen Xue-Chu  ,   (1)西南技术物理研究所，光电器件部，成都  610041; (2)中国科学院上海技术物理研究所，红外物理国家重点实验室，上海  200083; (3)中国科学院上海技术物理研究所，红外物理国家重点实验室，上海  200083；西南技术物理研究所，光电器件部，成都  610041
Published: December 2020

The optimum photo-thermal ionization range near liquid helium temperature for the shallow impurities in n type high purity silicon single crystal was determined experimentally. At temperature within this range, the high resolution photo-thermal ionization spectra (PTIS) of this sample were measured. Positive PTIS responses from the majority residual impurity phosphor (P) and compensating impurity boron (B) were observed by simultaneously irradiating the sample with far infrared and band-edge light. Under action of applied external magnetic fields, the positive response from compensating impurity B changes to negative response. The posibility of these phenomena being the result of temperature effect was excluded, which revealed the deficiency of Darken model and supported the model of rapid recombination of minority carriers for PTIS response of compensating impurity in elemental semiconductors.
Ab initio studies of CiCs and CiOi defects in Si1-xGex alloys
Authors: Yang Fu-Hua  , Tan Jin  , Zhou Cheng-Gang  , Luo Hong-Bo  ,   中国地质大学材料科学与化学工程学院，武汉  430074
Published: December 2020

Ab initio total-energy calculations were used to investigate the behaviors of CiCs and CiOi defects in Si and Si1-xGex alloys. It was found that in Si1-xGex alloys with different Ge contents, both CiCs and CiOi defects have good stability, and direct Ge—C or Ge—O bonds are unlikely to be formed. The A and B type structures of CiCs defects have similar characters in the alloys. The formation energy of A type configuration decreases with increasing Ge content. But the formation energy of B type decreases at first and then increases with the Ge content. The energy differences of A and B type configuration defects are between 0235 and 0220eV with lower Ge contents, and decrease sharply to around 01eV for higher Ge contents. The formation energy of CiOi pair displays a complex feature. Under isothermal annealing at 1000K and above, the structure of A type CiCs defect in pure Si was destroyed and transformed to B type defect. During annealing, the behavior of A type CiCs defect in Si1-xGex alloys depended on the annealing temperature, Ge content in the alloy, and the sites of Ge atoms.
Effect of sapphire substrate pre-treatment on the growth of ZnO films
Authors: Liu Ming  , Liu Zhi-Wen  , Gu Jian-Feng  , Qin Fu-Wen  , Ma Chun-Yu  , 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

Using the reactive radio-frequent magnetron sputtering method, ZnO thin films were deposited on pretreated (100) sapphire substrates. The effect of substrate pretreatments on the growth of ZnO films was studied with the structural and morphological characterization using atomic force microscopy, reflection high-energy electron diffraction and X-ray diffraction. It was found that both the original substrate and the substrates annealed in vacuum (8×10-4 Pa), nitrogen atmosphere (40 Pa), and oxygen atmosphere (40 Pa) at 750℃ for 4h have the same surface structure that can be indexed to be α-Al2O3 (001). The surface morphologies of the substrates are different from each other. All the ZnO films grown on the substrates are highly c-axis textured. Their morphologies, however, are related to the pretreatment. For the substrate annealed in vacuum, the film has the morphology with -c and +c epitaxial islands, similar to ZnO grown on the untreated substrate. For the substrate annealed in nitrogen, the film has the morphology with only -c epitaxial islands and has quite large grains and surface roughness. For the substrate annealed in oxygen, the films also has the morphology with -c epitaxial islands, but the surface is much smoother. The surface roughness is as small as 15nm.
The effect of the inserted AlGaAs films on the behaviors of InAs quantum dot detector
Authors: Wang Chong  , Liu Zhao-Lin  , Li Tian-Xin  , Chen Ping-Ping  , Cui Hao-Yang  , Xiao Jun  , Zhang Shu  , Yang Yu  , Lu Wei  ,   (1)云南大学工程技术研究院光电薄膜研究中心，昆明  650091; (2)云南大学工程技术研究院光电薄膜研究中心，昆明  650091；中国科学院上海技术物理研究所红外物理国家重点实验室，上海  200083; (3)中国科学院上海技术物理研究所红外物理国家重点实验室，上海  200083
Published: December 2020

Two InAs quantum dot samples have been grown by the solid source molecular beam epitaxy (MBE) and fabricated to detectors. AlGaAs thin films have been inserted into the source region for one of the two devices. The structural features of the two samples have been studied by using the transmission electron microscope (TEM). The photoelectric properties of them have been measured by the photoluminescence (PL) and photocurrent (PC) spectra. The experimental results indicated that the AlGaAs films have profound effects on the properties of the detector. According to the calculations based on effective mass approximation, the origins of the photocurrent peaks of the two devices have been identified.
Photo-induced effect of Mn site Fe doping in La0.67Sr0.33FexMn1-xO3 thin films
Authors: Tang Jing  , Chen Chang-Le  , Jin Ke-Xin  , Zhao Sheng-Gui  ,   西北工业大学凝聚态结构与性质陕西省重点实验室，西安  710072
Published: December 2020

The compounds and films of La067Sr033FexMn1-xO3(x=0, 005, 010, 015) were prepared by the sol-gel technique and pulsed laser deposition method, respectively. The effect of Fe doping on the transport and photo-induced properties of La067Sr033FexMn1-xO3 film was investigated. Experimental results indicate that the Fe doping lowers the insulator-metal transition temperature, but increases the resistance. The photo-induced relative change in resistance increases initially with increasing temperature, then followed by a decrease.The maximum value of the relative change in resistance increases with increasing x, it reaching 38％ when x =015 The intriguing mechanism of photo-induced effect on the resistance was discussed in connection with lattice effect.
Electronic structures of hydrogenated and oxygenated boron-doped diamond films
Authors: Liu Feng-Bin  , Wang Jia-Dao  , Chen Da-Rong  ,   清华大学摩擦学国家重点实验室,北京  100084
Published: December 2020

The hydrogenated and oxygenated boron-doped diamond films have been prepared by hydrogen-plasma treatment and boiling in the strong acids, respectively. By means of the X-ray photoelectron spectroscopy and contact angle measurements, the two surface-terminated diamond films have been evaluated. The scanning tunneling spectra have been measured by scanning probe microscope. The results indicated that for the hydrogenated diamond surface, the surface energy bands bend downwards and there exists a shallow acceptor above the valence band maximum. However, the surface energy bands for the oxygenated film bends upwards and its band gap is wide and clean. The conduction mechanisms for the two surface-terminated diamond films have been discussed.