bluuebunny/crossref_metadata_2025 huggingface dataset:
Variable separation solution and soliton excitations of the (1+1)-dimensional generalised shallow water wave equation
Authors: Shen Shou-Feng  ,   浙江工业大学数学系，杭州  310014
Published: December 2020

In this paper, variable separation solution and soliton excitations of the (1+1)-dimensional generalised shallow water wave equation are obtained. This equation includes two special cases which are completely integrable (IST integrable): the AKNS equation and the Hirota-Satsuma equation. Firstly, the variable separation (BT-VS) method based on the Bcklund transformation is extended to this eqaution for deriving VS solutions which include some low dimensional arbitrary functions. In the integrable cases, a space arbitrary function and a time arbitrary function are included. But in the other cases only a time arbitrary function is included and the space function needs to satisfy a specific condition. In addition, for the (1+1)-dimensional universal formula, abundant soliton excitations can be constructed, such as one-soliton, bell-anti-bell soltion, soliton expansion, breather-like, instaton-like. Finally, some discusions are made about the VT-VS method.
Chaos synchronization between the Sprott-B and Sprott-C with linear coupling
Authors: Liu Yang-Zheng  , Fei Shu-Min  ,   (1)东南大学自动控制系，南京  210096; (2)南京工程学院基础部，南京  210013;东南大学自动控制系，南京  210096
Published: December 2020

The Sprott-B and Sprott-C are topologically equivalent but they have distinct structures. Chaos synchronization is realized between the two systems via linear coupling of systemic variable. Based on Lyapunov stability theory, the threshold value of coupling coefficients for synchronization of two systems is derived. The practical circuit is designed to realize chaos synchronization between the two systems and the experimental result verifies the conclusion. A new method for secure communication, which can increase the security of a communication system is proposed based on chaos synchronization between the above systems.
Chaos control of Duffing systems by random phase
Authors: Li Shuang  , Xu Wei  , Li Rui-Hong  ,   西北工业大学理学院应用数学系,西安  710072
Published: December 2020

In this paper, the effect of random phase for Duffing systems is investigated. We show that random phase can generate chaos or suppress chaos by the average of top Lyapunov exponent, which is computed based on Khasminskii's spherical coordinate formulation for linear stochastic systems. In addition, phase portraits, Poincaré surface of section and time evolution are studied to confirm the obtained results. Both methods lead to fully consistent results.
Nuclear reaction dynamics induced by halo-nuclei at intermediate energy heavy ion collisions
Authors: Liu Jian-Ye  , Guo Wen-Jun  , Xing Yong-Zhong  , Lee Xi-Guo  , Zuo Wei  ,   (1)南京大学物理系,南京  210008; (2)天水师范学院数理信息学院基础物理研究所, 天水  741000;兰州重离子加速器国家实验室原子核理论中心，兰州  730000; (3)天水师范学院数理信息学院基础物理研究所, 天水  741000;中国科学院近代物理研究所，兰州  730000;兰州重离子加速器国家实验室原子核理论中心，兰州  730000; (4)中国科学院近代物理研究所，兰州  730000;兰州重离子加速器国家实验室原子核理论中心，兰州  730000
Published: December 2020

We studied systematically the reaction dynamics induced by neutron-halo nuclei and proton-halo nuclei within the isospin dependent quantum molecular dynamics,such as the effects of loose bound halo-nuclei on the fragmentation reaction and momentum dissipation for different colliding systems with different beam energies and different impact parameters. In order to emphasize the roles of neutron-halo nucleus 19B and proton-halo nucleus 23Al on the reaction dynamics wealso calculated the the reaction dynamics induced by the stable nuclei 19F and 23Na with equal mass under identical incident channel conditions. Based on the comparison of results of reaction dynamics induced by halo-nucleus colliding systems and stable nucleus collidinmg systems we found that the roles of loose bound halo-nucleus structure on the fragmentation multiplicity and nuclear stopping (momentum dissipation) are important for all of colliding systems with different beam energies and minor impact parameters, such as, the loose bound halo-nuclei structure increases the fragmentation multiplicity, but reduces the nuclear stopping.
Theoretical studies of dielectronic recombination and resonant transfer excitation for highly ionized Cu18+ ions
Authors: Dong Chen-Zhong  , Fu Yan-Biao  ,   (1)西北师范大学物理与电子工程学院,兰州  730070; (2)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重点实验室,兰州  730000
Published: December 2020

The dielectronic recombination cross sections of Cu18+ ions are calculated using a quasi-relativistic theory. The effects of configuration interaction to the cross sections are analysed. Base on the calculated data, the resonant transfer excitation cross sections of Cu18+ with H2 targets are estimated by using the convolution of Compton profile of the target electron in the impulse approximation. Good agreement of the present calculation with new experimental observation is achieved.
Confinement of fast ions in east tokamak
Authors: Zhang Jie  , Luo Jia-Rong  , Wang Shao-Jie  ,   (1)安庆师范学院物理与电气工程学院，安庆  246011; (2)中国科学院等离子体物理研究所，合肥  230031
Published: December 2020

The three well-known parameters of motion (magnetic momentum, energy and canonical toroidal momentum) are utilized to develop a guiding center orbit code, GCORBIT. The effect of poroidal field ripple and toroidal angle scatter is considered in the GCORBIT. It is applied to compute guiding center orbit of charged particle in axisymmetric tokamak, the loss region of velocity space and the loss fraction of fast ions.To compare achieved results, the loss region of velocity space by GCORBIT includes many effects: non-closed orbit of divertor, first orbit loss by guiding-center orbit being non-closed or intersecting with any material limiters, trapping by the poroidal field ripple in local magnetic wells, ripple random diffusion and toroidal angle scatter enabled by velocity space discontinuous confinement region. The GCORBIT is now being used to analyze the confinement of fast ions in EAST Tokamak. Our numerical calculations are focused on the loss of fast ions.
Principles of X-ray diffraction enhanced imaging
Authors: Zhu Pei-Ping  , Yuan Qing-Xi  , Huang Wan-Xia  , Wang Jun-Yue  , Shu Hang  , Wu Zi-Yu  , Xian Ding-Chang  ,   (1)中国科学院高能物理研究所同步辐射室,北京  100049; (2)中国科学院高能物理研究所同步辐射室,北京  100049;国家纳米科学中心协作实验室,北京  100049
Published: December 2020

The interactions between X-ray and the sample and crystals were investigated, and the influence of small angle scattering on images was emphatically analyzed in diffraction enhanced imaging in this paper. Not only were the additional noise term caused by small angle scattering introduced, and more general DEI equation established, but also expressions of absorption contrast, extinction contrast and refraction contrast were given for the peak image and the middle slope image. With the new DEI equation, the contrasts of two kinds of resultant images (apparent absorption image and refraction image) were discussed.
Molecular dynamics modelling of adsorption of HEDP on calcite surface
Authors: Xu Jing  ,   同济大学波耳固体物理研究所，上海  200092
Published: December 2020

The molecular dynamics modeling method is used to study the adsorption characteristics of 1-hydroxyethyldene-1,1-diphosphonic acid(HEDP) on the {104} surface of calcite. The simulated 3-D molecular graphs display that the oxygen atoms in the phosphonate groups of HEDP are strongly electro negative and have high affinity to cationic regions of the surface of the crystals, which results in the inhibitor molecular binding to the crystal surface to form the “multi-site stereo matching". The calculated results show that the adsorption energy of HEDP on the surface, step and kink are -5.2eV,-7.0eV and -23.5eV, respectively. It suggestes that HEDP malecules prefer to adsorb on the kinks to inhibit the development of steps on the calcite surface.
Design of an improved Fresnel prism
Authors: Tao Wei-Dong  , Wang Biao  ,   宁波大学理学院物理系，宁波  315211
Published: December 2020

Based on the optimization of the optical material and internal reflection angle, we designed a model of improved Fresnel prism that is insensitive to the angle of incidence. In this device, the incident light is reflected twice at the same internal reflection angle on the interface between two kinds of glass and the air. So the changes of retardation caused by reflection can compensate each other. The calculation shows that the departure of this kind of phase retarders is less than 0.36° when the angle of incidence changes between -2°　and +2°.It reserves the merits of normal incidence and normal output in archetypal Fresnel prism, and brings convenience in the operation.
Known-plaintext attack on double phase encoding encryption technique
Authors: Peng Xiang  , Zhang Peng  , Wei Heng-Zheng  , Yu Bin  ,   (1)深圳大学光电子学研究所，教育部光电子器件与系统重点实验室，深圳  518060; (2)深圳大学光电子学研究所，教育部光电子器件与系统重点实验室，深圳  518060;天津大学精密测试技术及仪器国家重点实验室，天津  300072; (3)天津大学精密测试技术及仪器国家重点实验室，天津  300072
Published: December 2020

In the field of optical information security, the most attractive work is the so-called double-random-phase encoding encryption scheme proposed by Javidi. However, the security of this cryptosystem has not been analyzed thoroughly from the point of view of cryptoanalysis. In this article, the weakness of Javidi's optical security system is carefully analyzed with a known-plain text attack. It is shown that the double-random-phase encoding encryption scheme is a linear symmetric block cipher cryptosystem and its linearity opens avenues of attacks. Under the known-plaintext attack, attacker can obtain the phase key(s) in the input plane using the typical phase retrieval algorithms and subsequently deduce the phase key(s) in the Fourier domain easily. In addition, an optical implementation of known-plain text attack is also proposed.
Design of multi-layer dielectric grating for femtosecond laser
Authors: Kong Wei-Jin  , Liu Shi-Jie  , Shen Jian  , Shen Zi-Cai  , Shao Jian-Da  , Fan Zheng-Xiu  ,   (1)中国科学院上海光学精密机械研究所，上海  201800; (2)中国科学院上海光学精密机械研究所，上海  201800;中国科学院研究生院，北京  100049
Published: December 2020

Based on optical interference theory and Fourier modal theory, a new multi-layer dielectric gratings is designed for use in femtosecond laser system at wavelength 0.8μm. A multi-layer dielectric with stack of H3L(HL)^9H0.5L2.4H is used as a substrate to be etched with corrugated structure. Numerical computation indicates that the diffraction efficiency of -1 order can be more than 95% when the parameters of multi-layer dielectric grating are the following: laser is incident on the grating at 36.7° in TE mode, the duty cycle is 0.35 and the line density is 1480/mm, the groove depth is 0.2μm and the top residual HfO2 is 0.15μm.
Electron holography investigation of the barrier of magnetic tunnelling junctions
Authors: Wang Yong  , Zhang Ze  , Zeng Zhong-Ming  , Han Xiu-Feng  ,   (1)北京工业大学，北京  100022; (2)中国科学院物理研究所，北京凝聚态物理国家实验室，北京  100080
Published: December 2020

Electron holography was successfully used to investigate the distribution of the potential of the barrier in magnetic tunnelling junctions experimentally and theoretically. We got a clear profile of the potential which shows a “well” in reconstructed phase profile. We also pointed out some artefacts in electron holographic study of magnetic tunnelling junctions and suggested some possible methods to resolve them.
Multifrequency dynamical model of pulsed CO2 lasers
Authors: Ding Chang-Lin  , Wan Chong-Yi  ,   (1)中国科学院电子学研究所，北京  100080; (2)中国科学院电子学研究所，北京  100080;中国科学院研究生院，北京  100049
Published: December 2020

A six-temperature multifrequency dynamical model of pulsed CO2 lasers is presented, taking account of the collision-dependent overlap of rotational lines, the effect of hot bands and sequence bands on the gain spectrum, and non-Lorentzian line overlap effect in a wide range of pressures from 20 torr to 20 atm. Theoretical calculations of pulse shape and laser spectrum have good agreement with experimental results. This model should be useful in the understanding of pulsed CO2 laser dynamics, in the evaluation of alternative pump schemes, and in the investigation of tunable characteristics. Thus it can provide theoretical support for the design of pulsed CO2 lasers.
High average power Q-switched quasi-continue-wave Nd:YAG laser
Authors: Bo Yong  , Geng Ai-Cong  , Bi Yong  , Sun Zhi-Pei  , Yang Xiao-Dong  , Li Rui-Ning  , Cui Da-Fu  , Xu Zu-Yan  ,   中国科学院物理研究所凝聚态物理国家实验室，北京  100080
Published: December 2020

A high-average-power and high-beam-quality diode-side-pumped solid-state Q-switched laser was developed by use of low concentration Nd:YAG crystals with thermally near-unstable resonator design and two-rod birefringence compensation technology. Two orthogonal acousto-optic Q-switches were used to sustain fully holding of the pump gain. The 1064 nm quasi-continuous-wave average output power of 258 W at pump power of 1116 W was achieved with the beam quality factor M2～15.5 at a repetition rate of 10 kHz and a pulse width of 64 ns, corresponding to a peek power of 0.4GW and an optical-to-optical conversion efficiency of 23.1%.
Doppler-free three-photon resonant six-wave mixing
Authors: Zuo Zhan-Chun  , Sun Jiang  , Wu Ling-An  , Fu Pan-Ming  ,   (1)河北大学物理系，保定  071002; (2)中国科学院物理研究所光物理实验室，北京  100080
Published: December 2020

We study the three-photon resonant six-wave mixing (SWM) with phase-conjugation geometry in Doppler system. The theoretical calculation indicates that the signal spectrum is Doppler-free when the laser line width is narrow. This technique provides a new spectroscopic tool for studying the highly excited atomic or molecular states with high resolution. It has advantages of uncritical phase matching condition, excellent spatial signal resolution and simple optical alignment.
High efficiency organic red electrophosphorescence devices with changing thickness of the emitting layer
Authors: Zhang Xiao-Bo  , Cao Jin  , Wei Fu-Xiang  , Jiang Xue-Yin  , Zhang Zhi-Lin  , Zhu Wen-Qing  , Xu Shao-Hong  ,   上海大学材料科学与工程学院，上海  201800
Published: December 2020

Devices using red phosphorescent dye as dopant with exciton blocking layer were constructed. The device structure is ITO/CuPc/NPB/TPBi:Btp2Ir(acac)/TPBi/Alq/LiF/Al. The EL spectra, luminance-current, efficiency-current characteristics of the device have been investigated. At the CIE coordinates x=0.62，y=0.35，efficiency 2.43cd /A has been achieved. At 20mA/cm2 and 400mA/cm2, luminance is 431cd/m2 and 4798 cd/m2, respectively. The effects of the emitting layer thickness on efficiency and EL spectra of the device have been studied also. With the decrease of the emitting layer thickness, efficiency decreases and the blue band of the El spectra increases. For the thickness d2Ir(acac) HOMO energy level. For the thickness d>20nm, the decrease of the efficiency is attributed to the added invalid emitting-layer and more annihilation centers.
Ultrashort pulse Yb3+-doped fiber ring laser with all-fiber structure
Authors: Huang Xiu-Jiang  , Liu Yong-Zhi  , Sui Zhan  , Li Ming-Zhong  , Li Xin  , Lin Hong-Huan  , Wang Jian-Jun  ,   (1)电子科技大学光电信息学院,成都  610054; (2)上海贝尔阿尔卡特股份公司研创中心,上海  201206; (3)中国电子科技集团公司第二十三研究所，上海  200437;电子科技大学光电信息学院,成都  610054;中国工程物理研究院激光聚变中心,绵阳  621900; (4)中国工程物理研究院激光聚变中心,绵阳  621900
Published: December 2020

Theory of the self-starting passive mode-locked Yb3+-doped fiber ring laser generating short pulses is presented. The ultrashort pulse Yb3+-doped fiber ring laser with all-fiber structure has been designed and turned out. Two 976nm LD pumped lasers are used as the pump sources and high concentration Yb3+-doped fiber is adopted as gain medium. Using the nonlinear polarization rotation (NPR) effect of the fiber, self-starting stable mode-locked pulse is obtained. The mode-locked threshold power of the laser is 260mW and the output power is 25mW. The center wavelength of the mode-locked pulse is 1056nm with 3dB bandwidth of 11.7nm at repetition rate of 20MHz. Comparing with the other structures of the fiber lasers, the structure we adopted is more efficient and has better stability.
Coherence enhancement of spatially incoherent light beams through soliton interaction in logarithmically saturable nonlinear media
Authors: Huang Chun-Fu  , Guo Ru  , Liu Si-Min  ,   南开大学物理学院, 天津  300071
Published: December 2020

We investigate numerically the interaction between incoherent spatial solitons in a nonlinear medium with logarithmic saturable nonlinearity base on the coherent density approach. Numerical simulations show that both the intensity and the spatial coherence can be greatly enhanced through soliton interaction. At the same time, we show that the soliton interaction can be controlled by the total partial incoherence, which can not only suppress the coherent soliton interaction such as attractive, repulsive or exchange energy, but also induce weak attractive due to incoherent superposition of two incoherent solitons.
Pump source angle tuning in quasi-phase matched optical parametric oscillator
Authors: Zhang Bai-Gang  , Yao Jian-Quan  , Lu Yang  , Ji Feng  , Zhang Tie-Li  , Xu De-Gang  , Wang Peng  , Xu Ke-Xin  ,   (1)天津大学精仪学院,天津  300072; (2)天津大学精仪学院,天津  300072;天津大学激光与光电子研究所,天津  300072;教育部光电信息技术科学重点实验室,天津  300072;南开大学、天津大学联合研究院,天津  300072
Published: December 2020

This paper systemically presents a theoretical analysis on pump source angle tuning in quasi-phase matched (QPM) optical parametric oscillator (OPO) in periodically poled crystal. The precise formula and the formula in paraxial approximation, both of which describe the relationship between rotation angle of pump source and wavelengths of pump, signal and idler wave in QPM OPO, are presented. It is found that the idler wave and the pump wave for signal-resonated OPO propagate along the same side of the crystal x-axis to exit, as propagate the signal wave and the pump wave for idler-resonated OPO. In addition, the separation angle between the signal wave and the idler wave for signal-resonated OPO is greater than that for idler-resonated OPO. More importantly, the tuning rate for signal-resonated OPO is also greater than that for idler-resonated OPO.
Optical properties of semiconductor quantum-well material using photonic crystal fabricated by micro-fabrication machine
Authors: Xu Xing-Sheng  , Xiong Zhi-Gang  , Sun Zeng-Hui  , Du Wei  , Lu Lin  , Chen Hong-Da  , Jin Ai-Zi  , Zhang Dao-Zhong  ,   (1)中国科学院半导体研究所光电子集成国家重点实验室,北京  100083; (2)中国科学院物理研究所,北京  100080
Published: December 2020

Two-dimensional photonic crystals in near infrared region were fabricated by using the focused ion beam (FIB) method and the method of electron-beam lithography (EBL) combined with dry etching. Both methods can fabricate perfect crystals, the method of FIB is simple,the other is more complicated. It is shown that the material with the photonic crystal fabricated by FIB has no fluorescence,on the other hand, the small-lattice photonic crystal made by EBL combined with dry etching can enhance the extraction efficiency two folds, though the photonic crystal has some disorder. The mechanisms of the enhanced-emission and the absence of emission are also discussed.
FDTD simulation for magnetized plasma photonic crystals
Authors: Liu Shao-Bin  , Gu Chang-Qing  , Zhou Jian-Jiang  , Yuan Nai-Chang  ,   (1)国防科技大学电子科学与工程学院，长沙  410073; (2)南京航空航天大学信息科学与技术学院，南京  210016; (3)南京航空航天大学信息科学与技术学院，南京  210016;南昌大学理学院，南昌  330047
Published: December 2020

Magnetized plasma photonic crystals are artificial periodic structures composed of magnetized plasmas and dielectric structures (or vacuum).In this paper,the piecewise linear current density recursive convolution (PLCDRC) finite-difference time-domain (FDTD) method for magnetized plasmas is applied to study the magnetized plasma photonic crystals.The effect of parameters of magnetized plasma on electromagnetic band gap is presented.In time-domain,the electromagnetic propagation process and reflection/transmission electric field of Gaussian pulses through magnetized plasma photonic crystals are investigated.In frequency-domain,the reflection and transmission coefficients through magnetized plasma photonic crystals are computed.The results are discussed.
Theoretical analysis of evanescent-wave atomic (molecular) guide using a bundle of four single-mode optical fibers
Authors: Ni Yun  , Yin Jian-Ping  ,   (1)光谱学与波谱学教育部重点实验室，华东师范大学物理系，上海  200062; (2)光谱学与波谱学教育部重点实验室，华东师范大学物理系，上海  200062;苏州大学物理系，苏州  215006
Published: December 2020

In this paper, we propose a new scheme to guide cold atoms (or cold molecules) using a bundle of four single-mode optical fibers with a sub-micrometer size, and calculate the evanescent-wave field in the hollow region of four-fiber bundle and its optical potential for 85Rb atoms. Our study shows that such a blue-detuned hollow evanescent-wave field can also be used to realize the laser waveguide of cold atoms (or cold molecules), and, compared with the traditional atomic guiding scheme using a hollow optical fiber, our scheme is not only simple and cheap, but also easier to realize the single-mode waveguide of cold atomic matter-wave with high efficiency.
Molecular dynamics simulation of the correlation between the viscosity and structure of liquid metal
Authors: Geng Hao-Ran  , Sun Chun-Jing  , Yang Zhong-Xi  , Wang Rui  , Ji Lei-Lei  ,   (1)济南大学材料科学与工程学院，济南  250022; (2)山东大学材料液态结构及其遗传性教育部重点实验室，济南  250061
Published: December 2020

The non-equilibrium molecular dynamics simulation (NEMD) has been performed based on the embeded atom potential to obtain the pair correlation function and the viscosity of liquid Al.The pair correlation function by the simulation agrees well with Waseda's X\|ray diffraction measurement.The temperature dependence of viscosity meets the Arrhenius formula:η=Aexp(E/RT) and the activation energy E calculated is 15968.27J/mol.The expression between the viscosity, pair correlation function and the inter-atomic potential has been obtained by application of the simulated viscosity value and the activation energy to meet L-J potential.The two fitted curves of viscosity agree well with that obtained by the NEMD method,showing the fitting program we compiled is excellent and the fitting to the L-J potential is achieved.This present work provides a new method to explore inter-atomic potential.
New computing methods and programs for separating multipe-broadening effects of X-ray diffraction lines
Authors: Qin Pei  , Lou Yu-Wan  , Yang Chuan-Zheng  , Xia Bao-Jia  ,   中国科学院上海微系统与信息技术研究所，上海  200050
Published: December 2020

The least square method and corresponding computing programs for separating twofold broadening effects due to the crystallite-microstress, crystallite-stacking faults, microstress-stacking faults and three-fold effect of crystallite-stress-faults have been proposed and established. The least square method can be applied to closed packing hexagonal (cph), face-centered cubic (fcc) and body-centered cubic (bcc) structures. A few examples are presented and discussed.
Simulation of dendritic growth of multicomponent alloys using phase-field method
Authors: Long Wen-Yuan  , Cai Qi-Zhou  , Wei Bo-Kang  , Chen Li-Liang  ,   (1)华中科技大学材料科学与工程学院,武汉  430074; (2)南昌航空工业学院材料科学与工程学院,南昌  330034
Published: December 2020

A phase-field model for multicomponent alloys based on the binary phase-field model has been developed. The isothermal dendritic growth of Al-Si-Mg alloys is presented as a numerical example, accordingly, the dendrite growing morphology of multicomponent alloys solidification could be simulated realistically using the phase-field model. As the result, the intricate figures such as secondary and tertiary dendrite arms are revealed. The decrease of solute Mg can trigger the growth of the secondary arms and increase the solute microsegregation rate, the tip speed and radius of dendrite. The variation of the speed and the radius in the dendrite tip agrees well with theoretical and experimental results in succinonitrile-acetone system. In addition, the spines of the primary arms have lowest concentration, and the mushy regions between the dendrite secondary arms have the highest concentration; the solute gradients are higher in the vicinity of the S/L interface regions, and highest in the tip.
Study of low energy sputtering of Pt(111) surface by molecular dynamics simulation
Authors: Yan Chao  , Lü Hai-Feng  , Zhang Chao  , 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

Low energy sputtering of Pt (111) surface by noble metal atoms with the incident energy in the range of 0.1 — 200 eV has been studied by molecular dynamics sim ulation. The atomic interaction potential with embedded atom method (EAM) was us ed in the simulation. It was found that the sputtering threshold energy is indep endent of the mass of the incident atom in the case of normal impact on the Pt ( 111) surface. When the incident energy is lower than the threshold energy, the b ehavior of incident atom can be regarded as deposition process. When the inciden t energy is higher than the threshold energy, however, the sputtering yield incr eases with the increase of the incident energy. For the incident energy of 200 e V, the sputtering yield induced by various incident atoms approaches 1 or even h igher. The results mean that the atom with incident energy higher than 200 eV ma inly plays the role of sputtering. The probability of angular distribution of th e sputtered atoms and the sputtering pattern are similar to the sputtering resul ts with higher incident energy. We found that the sputtering yield is a function of the reduced energy of incident atom and the mass ratio of incident atom to t arget atom when the incident energy is higher than the threshold energy, which i s different from the linear cascade theory based on the binary collision model. We suggest a new physical mechanism for low energy sputtering, where the reflect ion of incident atom by target atom dominates the sputtering process of surface atoms.
Study of persistent photoconductivity and subband electronic properties of the two-dimensional electron gas in modulation doped GaAs/AlGaAs structure
Authors: Shu Qiang  , Shu Yong-Chun  , Zhang Guan-Jie  , Liu Ru-Bin  , Yao Jiang-Hong  , Pi Biao  , Xing Xiao-Dong  , Lin Yao-Wang  , Xu Jing-Jun  , Wang Zhan-Guo  ,   (1)南开大学泰达应用物理学院，南开大学弱光非线性光子学材料及其先进制备技术教育部 重点实验室，天津  300457; (2)南开大学泰达应用物理学院，南开大学弱光非线性光子学材料及其先进制备技术教育部 重点实验室，天津  300457;中国科学院半导体研究所半导体材料科学重点实验室,北京  100083
Published: December 2020

We obtained the high mobility of μ2K=1.78×106 cm2/V·s in Si-doped GaAs/AlGaAs two-dimensional electron gas (2DEG) structures . After the sample was illuminated by a light-emitting diode in magnetic fields up to 6 T at T=2K, we did observe the persistent photoconductivity effect and th e electron density increased obviously. The electronic properties of 2DEG have b een studied by Quantum-Hall-effect and Shubnikov-de Haas (SdH) oscillation measu rements. We found that the electron concentrations of two subbands increase simu ltaneity with the increasing total electron concentration, and the electron mobi lity also increases obviously after being illuminated. At the same time, we also found that the electronic quantum lifetime becomes shorter, and a theoretical e xplunation is given through the widths of integral quantum Hall plateaus.
Influences of growth temperature on the crystalline characteristics and optical properties for ZnO films deposited by reactive magnetron sputtering
Authors: Sun Cheng-Wei  , Liu Zhi-Wen  , Qin Fu-Wen  , Zhang Qing-Yu  , Liu Kun  , Wu Shi-Fa  ,   (1)大连理工大学三束材料改性国家重点实验室，大连  116024; (2)大连理工大学物理系，大连  116024
Published: December 2020

Using reactive radio-frequency magnetron sputtering, ZnO films with strong c-axi s orientation have been deposited on Si (100) substrates at temperatures ranging from room temperature (RT) to 750℃. We have studied the influence of growth te mperature on the structural characteristics of the as-deposited films in morphol ogy, grain size, microstructure, and residual stress by using atomic force micro scopy, transmission electron microscopy, X-ray diffraction, and Raman spectrosco py. With the measurement of the transmission spectra and photoluminescence (PL) properties, the relationship between the crystallinity and optical properties of ZnO films have been discussed. It is found that the grain size increases with t emperature up to 500℃, and then decreases at 750℃. ZnO grains have an epitaxia l relationship with Si (100) substrate for the films deposited at the temperatur es ranging from RT to 750℃. The films deposited below 500℃ are in the states o f compressive strain while the film deposited at 750℃ is in tensile. The differ ence in growth temperature results in the variation of refractive index, extinct ion coefficient, optical energy gap, and PL properties of the films. It is concl uded that growth temperature dominates the PL behavior of ZnO films. We also dis cuss the physical mechanism affecting the PL behavior.
The effects of passivation and temperature on the barrier strain of Al0.22Ga0.78N/GaN heterostructures
Authors: Zhang Kai-Xiao  , Chen Dun-Jun  , Shen Bo  , Tao Ya-Qi  , Wu Xiao-Shan  , Xu Jin  , Zhang Rong  , Zheng You-Dou  ,   (1)北京大学人工微结构和介观物理国家重点实验室，北京大学宽禁带半导体研究中心，北 京  100871; (2)河海大学理学院，南京  210098;江苏省光电材料重点实验室，国家微结构重点实验室，南京大学物理系，南京  210093; (3)江苏省光电材料重点实验室，国家微结构重点实验室，南京大学物理系，南京  210093
Published: December 2020

The barrier strain in Al0.22Ga0.78N/GaN heterostructure, w ith and without Si3N4 passivation layer, was investigated at temperatures from room temperature to 813K by using high resolution X-ray dif fraction. The strain relaxation occurs when the temperature exceeds 523K for the unpassivated Al0.22Ga0.78N layers. After passivation, an initial increase of the strain with increasing temperature is observed in Al0.22Ga0.78N layers, and at the higher temperatures the strain only decreases slightly in the 100-nm-thick Al0.22Ga０.78N layer, but a pronounced strain relaxation occurs in the 50-nm-thick one due to the fact that the thickness of the A10.22Ga0.78N layer is close to the critical thickness, and hence the increase of tensile strain induce d by passivation will result in partial strain relaxation via the formation of c racks or the gliding motion and multiplication of dislocations.
Kondo effect in parallel double quantum dots embedded in a mesoscopic ring
Authors: Wu Shao-Quan  , He Zhong  , Yan Cong-Hua  , Chen Xiong-Wen  , Sun Wei-Li  ,   四川师范大学物理系、固体物理研究所，成都  610068
Published: December 2020

We theoretically studied the properties of the ground state of the parallel-coup led double quantum dot embedded in a mesoscopic ring in the Kondo regime by mean s of the two-impurity Anderson Hamiltonian. The Hamiltonian is solved by means o f the slave-boson mean-field theory. Our results show that when the system goes into the strong coupling regime, two parallel dots can be coupled coherently, wh ich leads to an enhanced Kondo effect and a giant persistent current emerging in this system. This double quantum dot device can be a candidate for future devic e applications.
Negative bias temperature instability of HfN/HfO2 gated p-MOSFETs
Authors: Sa Ning  , Kang Jin-Feng  , Yang Hong  , Liu Xiao-Yan  , Zhang Xing  , Han Ru-Qi  ,   北京大学微电子所，北京  100871
Published: December 2020

The negative-bias temperature instability (NBTI) characteristics of HfN/HfO 2 gated p-MOSFET with equivalent oxide thickness (EOT) of 1.3nm and low pre-existi ng traps are studied. Due to the low pre-existing trap density of HfN/HfO2 ga te stack, the observed NBTI characteristics are intrinsic, rather induced by the fabricating process. The observed characteristics can be compared with those re ported in SiO2 based gate stack and can be explained with the general ized reac tion-diffusion (R-D) model: under negative bias and temperature stressing, holes injected from the Si substrate could cause the Si-H bond breaking at the Si sub strate interface. The H atoms diffuse away into the bulk layer and the Si+ spe cies are left at the interface. The diffusing H atoms and the left Si+ species cause the NBTI characteristics.
Influence of the stress on the transport behavior of La0.83Sr0.17MnO3 film
Authors: Jiang Kuo  , Li He-Fei  , Gong Sheng-Kai  ,   北京航空航天大学材料学院，北京  100083
Published: December 2020

The LSMO (x=0.17) film on the Si (111) substrate was fabricated by the sol-gel m ethod.The R-T curves, the infrared spectra and XRD results of the block and the film with different thickness show that the crystals of the LSMO films are orth ogonal, and the film orientation has some relation with the film thickness. Whe n the film thickness lies between the 450nm to 680 nm, the orientation is 〈200 〉, but when the film thickness equals to 900 nm, the orientation is 〈020〉. Ac cording to the reactive energy and the harmonic oscillator model, the relational expressions, between the infrared absorption and the Mn-O-Mn bond length and bo nd angel were studied. The infrared absorption near 600cm-1 relates t o the different lattice constant b, and the metal-insulator transformation tempe ratures (TMI) of the block material and the films differ much, those of the films being much lower than that of the block material and, at the same time, has something to do with the film thickness. The paper indicates that the stress in the LSMO films inducing the lattice constant change and then arousing the change of bond angel and JT effect is the main reason for the change of the transformation temperature.
Colossal magnetoresistance effect in the perovskite-type La1－xPrxMnO3 thin films
Authors: Duan Ping  , Chen Zheng-Hao  , Dai Shou-Yu  , Zhou Yue-Liang  , Lü Hui-Bin  ,   (1)天津大学应用物理系，天津  300072;中国科学院物理研究所，北京  100080; (2)中国科学院物理研究所，北京  100080
Published: December 2020

The oxide La1-xPrxMnO3 (x=0.1, 0.2) thin film s howing colossal magnetoresistance has been epitaxially grown on (100) SrTiO 3 single-crystal substrate by pulsed-laser deposition. The films have a pe rovskite structure and perform the colossal magnetoresistance effect with the ma ximum magnetoresistance ratio of 95% under the magnetic field of 5 T. The valenc e of Pr is confirmed as +4 through XPS. Therefore the epitaxial film is most lik ely an electron-doped colossal magnetoresistance fihn.
Effect of Mn substitution on the structure and magnetic properties of Dy2AlFe16－xMnx compounds
Authors: Hao Yan-Ming  , Zhou Yan  , Zhao Miao  , Fu Bin  ,   天津师范大学物理系，天津  300074
Published: December 2020

The structural and magnetic properties have been investigated by means of X-ray diffraction and magnetization measurements. The Dy2AlFe16-xMnx compounds have a hexagonal Th2Ni17-type st ructure. The thermal expansion of Dy2AlFe16-xMnx (x=1 and 2) compounds have been investigated by X-ray dilatometry in the tempe rature range 104—647K. The results show that there is a thermal expansion anoma ly at low temperature and a negative thermal expansion near the Curie temperatur e. There exists a strong and anisotropic spontaneous magnetostriction in the mag netic state of Dy2AlFe16-xMnx compounds. The sp ontaneous volume magnetostrictive deformation at low temperature decreases with increasing x. The result of magnetization measurement shows that the Curie tempe rature and the spontaneous magnetization of Dy2AlFe16-xMnx compounds at 5K decrease rapidly with increasing x.
Room-temperature ferromagnetism in bulk CoxTi1－xO2－δ induced by the phase transformation in the hydrogenation sintering process
Authors: Kong Ling-Gang  , Kang Jin-Feng  , Wang Yi  , Liu Li-Feng  , Liu Xiao-Yan  , Zhang Xing  , Han Ru-Qi  ,   北京大学微电子学研究所,北京  100871
Published: December 2020

Paramagnetic (Co3O4)x/3(TiO2)1- x(03O4 and TiO2 from 700 ℃ to 1000 ℃ in air. X-ray diffraction (XRD) re sults showed that perovskite CoTiO3 existed in all samples. Anatase p hase was also detected in samples sintered at 700 ℃ and when sintering the mixt ure at above 900 ℃, rutile phase formed with anatase phase disappearing. All sa mples exhibited room-temperature ferromagnetism (RTFM) after being hydrogenated in 10％ H2/Ar mixed atmosphere for 1 hour at 500 ℃. X-ray photoelect ron spectroscopy (XPS) showed that Co existed in the +2 formal oxidation state, and no Co clusters were detected. XRD showed that CoTiO3 disappeared and a new phase CoxTi1-xO2-δ formed after hyd rogenation. It is suggested that hydrogenation causes the phase transformation f rom CoTiO3 to CoxTi1-xO2-δ. RTFM of the sample originates from the intrinsic ferromagnetism of CoxTi1-xO2-δ. The exchange interaction between Co2+ occ urring with the phase transformation may be the essential reason for RTFM.
Deposition of diamond-like carbon and analysis of ion energy in CH4 or CH4+Ar dielectric barrier discharge plasma
Authors: Liu Yan-Hong  , Zhang Jia-Liang  , Wang Wei-Guo  , Li Jian  , Liu Dong-Ping  , Ma Teng-Cai  ,   (1)大连理工大学等离子体物理化学研究室，大连  116024; (2)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

Diamond-like carbon (DLC) films were deposited by dielectric barrier discharge ( DBD) from CH4 or CH4 +Ar at pressure of several hundred Pa . The dependence of the film hardness on the product of p and d (p is the gas pr essure and the d is the discharge space) and Ar volume concentration (RAr) was investigated experimentally. The kinetic energies of CH+4 and Ar+ ions were analyzed theoretically based on the two-t emperature model for high reduced field E/n (the ratio of electric field strengt h to the gas number density), in which ions were assigned a temperature much hig her than the gas temperature, on the Langevin equation in other gas and on the B lanc law in mixed gases. The results showed that, 1) for CH4 DBD, whe n decreasing pd from 1.862×103Pa mm to 2.66×102Pa mm, th e kinetic energy of CH+4 increases from 5.4 to 163eV, whil e the hardness of deposited DLC films increases from 2.1 to 17.6 GPa. 2) For CH+4Ar DBD, when increasing Ar volume concentration from 20% to 83%, the kinetic energy of CH+4 increases from 69 to 92 eV, whereas the kinetic energy of Ar+ decreases from 93 to 72eV. The increase of film hardness with increasing Ar volume concentration up to 67% can be attributed to the increase of CH+4 kinetic energy. Howe ver, the impinging of energetic Ar+ on the film surface reduces the f ilm hardness owing to graphitization. For verification of the theoretical model on ion energy analysis, the kinetic energy of ions in H2 DBD were mea sured and compared with that from theoretical analysis.
Upconversion emission properties of Er3+ in fluoride (halide) phosphate tellurite glasses
Authors: Wen Lei  , Zhang Li-Yan  , Yang Jian-Hu  , Wang Guo-Nian  , Chen Wei  , Hu Li- Li  ,   (1)中国科学院上海光学精密机械研究所，上海  201800; (2)中国科学院上海光学精密机械研究所，上海  201800;中国计量学院信息工程学院光通讯材料与器件研究所，杭州  310018
Published: December 2020

The absorption and upconversion spectra of Er3+-doped fluoride (halid e) phosphate tellurite glasses were investigated for the first time, and the upc onversion mechanisms were studied. Strong red and green upconversion luminescenc e were observed under 975nm laser diode excitation at room temperature. When PbF 2 is partially replaced by PbCl2 gradually, the intensity of red emission decreases, while the green emission intensity changes only sligh tly. When ZnF2 is replaced by 5mol% ZnCl2, both red and gr een emissions intensity are enhanced obviously.
Memory characteristics of metal-ferroelectric-semiconductor field-effect-transistors with Ag/Bi4Ti3O12/p-Si gate
Authors: Wang Hua  , Ren Ming-Fang  ,   桂林电子工业学院信息材料科学与工程系,桂林  541004
Published: December 2020

Metal-ferroelectric-semiconductor field-effect-transistors (FFETs) with Ag/Bi4Ti3O12/p-Si gate were fabricated using the high q uality Bi4Ti3O12 on p-Si substrates prepared by Sol-Gel technique. The phase structure characteristics of Bi4Ti 3O12 films, the interface characteristics of ferroelectric/Si a nd the memory characteristics of the FFETs were investigated. Bi4Ti 3O12 films with high preferred c-axis-orientation are obta ined at appropriate annealing temperature which helps to improve the interface c haracteristics of ferroelectric/Si. The C-V hysteresis curves with clockwise loo ps prove that the FFETs could realize a memory effect due to the ferroelectric p olarization of Bi4Ti3O12 films, and the capacit ance decay of 11% in 16 hours indicates that the FFETs have good polarization ch arge retention. The counter-clockwise Ids-VG hysterisis cu rve of the FFETs demonstrates that the channel current is modulated by the ferro electric polarization of Bi4Ti3O12 films.
Application of the homotopy analysis method to solving nonlinear evolution equations
Authors: Shi Yu-Ren  , Xu Xin-Jian  , Wu Zhi-Xi  , Wang Ying-Hai  , Yang Hong-Juan  , Duan Wen-Shan  , Lü Ke-Pu  ,   (1)兰州大学理论物理研究所,兰州  730000; (2)兰州大学理论物理研究所,兰州  730000;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
Published: December 2020

We obtained a class of approximate periodic solutions for the (2+1)-dimensional modified Zakharov-Kuznetsov equation by using the homotopy analysis method (HAM). The solutions we got agree with the exact solutions. The results indicate that the HAM is still valid for solving a class of higher dimensional evolution equations. We also made some efforts to extend the HAM to find the analytical solutions for more nonlinear evolution equations in an easier way.
Exact quantization rule and the invariant
Authors: Ma Zhong-Qi  , Xu Bo-Wei  ,   (1)上海交通大学物理系,上海  200030; (2)中国科学院高能物理研究所,北京  100049
Published: December 2020

We present and prove the exact quantization rules both for the one-dimensional Schrdinger equation and for the three-dimensional Schrdinger equation with a spherically symmetric potential. In the exact quantization rule, in addition to the usual term Nπ, there is an integral term, called the correction term. For the quantum systems with a so-called shape invariant potential in the supersymmetric quantum mechanics, we find that the correction term is an invariant,independent of the number of nodes in the wave functions. In those systems, the invariant can be determined with the help of the energy and the wave function of the ground state, and then, the energy levels of all the bound states can be easily calculated from the exact quantization rule. Conversely, the validity of the calculated energy levels shows that the correction term is an invariant in those quantum system with a shape invariant potential. The systems with a shape invariant potential we calculated in this paper are the one-dimensional systems with a finite square well, with the harmonic oscillator potential, with the Morse potential and its generalizations, with the Rosen-Morse potentials, with the Pschl-Teller potentials, with the Eckart potential, and with the Hulthen potential, and the three-dimensional systems of harmonic oscillators and the hydrogen atom.
Rigid multibody molecular dynamics algorithm in canonical ensemble
Authors: Yu Da-Qi  , Chen Min  ,   清华大学工程力学系,北京  100084
Published: December 2020

By specializing the Hamiltonian of Nose's extended system in rigid multibody systems, we develop rigorous motion equations for rigid multibody molecular dynamics in canonical ensemble. The equations are proved to generate correct canonical equilibrium distributions. The corresponding reversible and symplectic integrator is also given in this paper.
The synchronization of hyper-chaotic system of cellular neural network based on passivity
Authors: Wu Zhong-Qiang  , Tan Fu-Xiao  , Wang Shao-Xian  ,   燕山大学电气工程学院,秦皇岛  066004
Published: December 2020

Based on a certain characteristic of cellular neural network hyper-chaotic system, an error system for the drive system and response system is got, and the problem of synchronization of hyper-chaotic system is put forward thereupon. The problem is to ensure the global approximate stability of the synchronization error system. A kind of passivity method is adopted to design stable feedback controller to ensure global approximate stability of the error system. The simulation result of the hyper-chaotic system of four order cellular neural network testifies the validity of the method.
Density functional theory study on the structure and properties of MgmBn(m=1,2;n=1—4) clusters
Authors: Chen Yu-Hong  , Zhang Cai-Rong  , Ma Jun  ,   (1)兰州理工大学理学院，兰州  730050; (2)兰州理工大学理学院，兰州  730050;兰州理工大学省部共建有色金属新材料国家重点实验室，兰州  730050
Published: December 2020

Possible geometrical structures and relative stability of MgmBn(m=1,2;n=1—4) clusters are studied by using the hybrid density functional theory(B3LYP) with 6-31G basis sets. For the most stable isomers of MgmBn(m=1,2;n=1—4) clusters, the electronic structure, vibrational properties, bond properties, ionization potential, polarizability and hyperpolarizability are analyzed. The calculated results show that most of the optimized MgmBn(m=1,2;n=1—4) clusters have planar structure, the B-B and B-Mg bonds are coexisting in the cluster, but the Mg-Mg bonds are infrequent in the clusters. The bond length of B-B is about 0.153—0.182nm and that of Mg-B is 0.221—0.231nm. The outcome of population analysis suggests that there is an electronegative center in the cluster, the other B and Mg atoms with positive charge are located at apexes of the cluster.
Diode-end-pumped CW Tm,Ho:YLF solid-state laser working at room temperature
Authors: Zhang Xin-Lu  , Wang Yue-Zhu  , Shi Hong-Feng  ,   (1)哈尔滨工业大学光电技术研究所，可调谐激光国家重点实验室,哈尔滨  150001; (2)哈尔滨工业大学光电技术研究所，可调谐激光国家重点实验室,哈尔滨  150001;哈尔滨工程大学理学院,哈尔滨  150001
Published: December 2020

The laser properties of laser diode end-pumped Tm and Ho co-doped lithium yttrium fluoride (YLF) laser are studied. The experiment of Tm,Ho:YLF laser is conducted for different output couplings, and the optimum output coupler transmission is 2% when the crystal is kept at room temperature. The distribution of far field intensity is measured by pin-hole scanning, the output laser is proved to be operating in the TEM00 mode, and the relation between thermal focal length and pump power is obtained. To achieve single frequency operation, two solid, uncoated fused silica etalons are used. The laser threshold pump power is 250 mW, and the maximum continuous wave single frequency output power is 118 mW at the pump power of 2.8 W. The single frequency laser may be used as a seed laser for either a larger oscillator or an amplifier.
Effect of initial chirp on supercontinuum generation by femtosecond pulse in photonic crystal fibers
Authors: Liu Wei-Hua  , Wang Yi-Shan  , Liu Hong-Jun  , Duan Zuo-Liang  , Zhao Wei  , Li Yong-Fang  , Peng Qin-Jun  , Xu Zu-Yan  ,   (1)陕西师范大学物理学与信息技术学院，西安  710062; (2)中国科学院物理研究所，北京  100080; (3)中国科学院西安光学精密机械研究所瞬态光学与光子技术国家重点实验室，西安  710068; (4)中国科学院西安光学精密机械研究所瞬态光学与光子技术国家重点实验室，西安  710068;陕西师范大学物理学与信息技术学院，西安  710062
Published: December 2020

The numerical simulations with the method of split-step Fourior were presented to investigate the effect of initial chirp on supercontinuum generation in photonic crystal fibers. According to the fiber length, the evolution of pulse in photonic crystal fibers was divided into three stages: initial broadening stage, dramatic broadening stage and saturation broadening stage. By discussing the differences in evolution of the chirp pulse and non-chirp pulse in each stage, we find that the initial chirp only affects the spectrum at the initial broadening stage and the dramatic broadening stage, and the chirp is profitable for spectrum broadening when β2C2C>0. In the saturation broadening stage, chirp does not affect the spectrum anymore. If we want to broaden the spectrum by using chirp pulse we must choose a right fiber length, and output the pulse in the dramatic broadening stage. These conclusions provide significant reference for supercontinuum generation in photonic crystal fibers with chirp pulse.