bluuebunny/crossref_metadata_2025 huggingface dataset:
The microstructure and impact toughness of sintered Nd-Fe-B magnets
Authors: Hu Zhi-Hua  , Lian Fa-Zeng  , Zhu Ming-Gang  , Li Wei  ,   (1)东北大学材料各向异性与织构教育部重点实验室，沈阳  110004; (2)东北大学材料各向异性与织构教育部重点实验室，沈阳  110004；钢铁研究总院功能材料研究所，北京  100081; (3)钢铁研究总院功能材料研究所，北京  100081
Published: December 2020

The effects of Nb on the microstructure and impact toughness of sintered Nd-Fe-B magnets as well as their inter relation have been investigated. The results show that the addition of Nb improves the microstructure, and increases impact toughness of sintered magnets. When Nb content of the sintered magnets without Co is 15 at%，the maximum impact toughness is obtained. But for the sintered magnets with the Co addition, the variation of impact toughness of the magnets is not obvious, and the magnets have lower impact energy than the magnets with the Co addition. The microstructure of sintered magnets has been studied. It was found that many factors affect the impact toughness of sintered magnets, but the main factor is the width and shape of grain boundary of sintered magnets.
Built-in electric field and a new type of charged excitons observed in modulation-doped ZnSe/BeTe type-Ⅱ quantum well
Authors: Ji Zi-Wu  , Lu Yun  , Chen Jin-Xiang  , Mino Hirofumi  , Akimoto Ryoichi  , Takeyama Shojiro  ,   (1)产业技术综合研究所超高速光学器件研究实验室，茨城  305-8568，日本; (2)东京大学生产技术研究所,东京  153-8505，日本; (3)东京大学物性研究所,柏  277-8581，日本; (4)千叶大学工学部城市环境系统学科，千叶大学自然科学研究科，千叶  263-8522，日本
Published: December 2020

We report results of the photoluminescence, photoluminescence excitation, and magneto-photoluminescence spectra measurements performed on modulation doped ZnSe/BeTe/ZnSe type-Ⅱ quantum well structures at low temperature (2—5 K). The non-doped sample showed two distinct peaks, while the doped one showed one peak only. The linear polarization degree measured in both photoluminescence and the photoluminescence excitation spectroscopy indicates that photoluminescence transitions of an indirect type takes place at respective heterointerfaces. The peak splitting in the non-doped sample was caused by a built-in electric field resulting from the spatial separation of charges along the growth axis. We found optical Shubinkov-de Hass oscillations in both the photoluminescence intensity and the transition energy under a high magnetic field perpendicular to the well. These features and the additional absorption (or reflection) spectra measurements demonstrated that two-dimensional electron gas of a high concentration was formed in the doped samples. All these present the signature of charged excitons and also of a correlated excitonic phase of type-Ⅱ quantum wells.
RF magnetron sputtering deposition growth of highly orientated strontium barium niobate thin films
Authors: Li Yue-Fu  , Ye Hui  , Fu Xing-Hai  ,   浙江大学现代光学仪器国家重点实验室，杭州  310027
Published: December 2020

The ferroelectric potassium ion doped Sr075Ba025Nb2O6(SBN75) buffer layers were fabricated on Si(100) substrate by the sol-gel method, and the highly c-axis preferentially orientated SBN thin films on the KSBN buffer layers were obtained by the RF magnetron sputtering deposition. For the deposition of films, the corresponding preparation parameters have been optimized. It was found that the KSBN buffer layers can reduce the mis-match of crystalline lattices between the SBN film and the substrate effectively. When the ratio of O2/Ar pressure reached 1∶2, the working pressure was 10 Pa, and the sputtering power was 300W, the temperature of substrate was 300℃ and the post-annealing temperature was adjusted to 800℃, the c-axis highly preferentially orientated growth of SBN thin film can be realized. The microstructure of the thin films was investigated by XRD and AFM, and the p-n junction effect was found in our ITO/SBN/KSBN/Si structures, which is characteristic of semiconductor materials. The intensity of the junction effect was closely related to the presence of the buffer layer as well as the crystalline properties of SBN thin films.
Epitaxial growth of high quality TiN thin film on Si by laser molecular beam epitaxy
Authors: He Meng  , Liu Guo-Zhen  , Qiu Jie  , Xing Jie  , Lü Hui-Bin  ,   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

TiN thin films have been successfully epitaxially grown on Si substrates by laser molecular-beam epitaxy using the two-step method. The thin film has a smooth surface with a root-mean-square roughness of 0842nm over a 10μm×10μm area. Hall measurement shows that the resistivity of the TiN film is 36×10-5 Ω·cm and the mobility is up to 5830 cm2/V·S at room temperature，which implies that TiN thin film is an excellent electrode material. The X-ray diffraction (XRD) θ—2θ scan result together with the very high mobility show that the TiN film has high quality. The result that SrTiO3 thin film can be subseguently epitaxially grown on TiN/Si substrate indicates that the TiN thin film on Si substrate not only has good thermal stability, but also can be used as buffers or bottom electrode for epitaxial growth of other thin films or multilayer films.
The effect of static electric field on nonsequential double ionization
Authors: Li Hong-Yun  , Wang Bing-Bing  , Jiang Hong-Bing  , Chen Jing  , Li Xiao-Feng  , Liu Jie  , Gong Qi-Huang  , Fu Pan-Ming  ,   (1)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; (2)应用物理与计算数学研究所非线性研究中心，北京  100088; (3)中国科学院物理研究所光物理实验室，北京  100080
Published: December 2020

Nonsequential double ionization of He atom in the combined field of a laser and a static electric field has been investigated. It is found that the presence of the static electric field breaks the inversion and reflection symmetry, the symmetric double-peak structure of the He2+ ion momentum parallel to the polarization of the laser field is broken. Since the ultrashort laser pulse has the similar asymmetric character, this study is helpful to understand the mechanism of the double ionization process in ultrashort laser field.
The asymptotic analysis of interfacial stability with surface tension anisotropy for directional solidification of alloys
Authors: Wang Zhi-Jun  , Wang Jin-Cheng  , Yang Gen-Cang  ,   西北工业大学凝固技术国家重点实验室，西安  710072
Published: December 2020

An asymptotic analysis of interfacial stability with the surface tension anisotropy is derived for directional solidification of alloys. The zero and first order solution for multi-scale and the zero order solution for single-scale are obtained. The dispersion relation adapted to all wave-length is presented by combining the short and the long wave-length solutions. It was concluded that the zero order asymptotic solution is equivalent to constitutional undercooling theory and the first order solution is consistent with M-S theory. The instability zone of control parameter enlarges with the surface tension anisotropy,especially for the high temperature gradient and high pulling velocitycases.
Hawking radiation of Dirac particles in a rectilinearly accelerating Kinnersley black hole
Authors: Yang Bo  ,   重庆三峡学院物理与电子工程学院，重庆  404000
Published: December 2020

In a uniformly accelerating space time, the coupling Dirac equation can be simplified to the second-order equation. Using new tortoise coordinates, we further simplify the equation to the standard wave-equation near the horizon and get the temperature function of radiation and the Hawking radiation spectrum.
A special nonholonomic mechanical system calculated by symplectic method
Authors: Liu Shi-Xing  , Guo Yong-Xin  , Liu Chang  ,   辽宁大学物理学院，沈阳  110036
Published: December 2020

This paper studies numerically a special nonholonomic mechanical system. A better algorithm of structure-preserving is adopted to calculate numerically and compare it to the classical R-K method. By comparing the results of two methods, the advantage of symplectic method used on this special nonholonomic mechanical system is presented.
Optical-optical double-color and double-resonance multiphoton ionization spectrum of NO2
Authors: Zhang Gui-Yin  , Jin Yi-Dong  ,   华北电力大学数理系，保定  071003
Published: December 2020

The optical-optical double resonance multiphoton ionization (OODR-MPI) technique has been applied to the study of the Rydberg states of nitrogen dioxide. The results show that NO2 molecule is ionized though a 1+3+1 double resonance multiphoton ionization process in 605—675nm probe wavelength region. The ionization pathway is: NO2(X2A1)hν1NO2(A2B2)3hν2NO2(3pσu)hν2NO22+e. The OODR-MPI spectrum corresponds to the excitation of NO2 3pσu Rydberg state by a three photon process. The value　ω1=(1422.5±23.5) cm-1 and ω2＝(590.5±4.9) cm-1 of symmetric stretching and bending vibration frequencies of this Rydberg state are presented. The position of the band origin and the quantum defect of 3pσu Rydberg state are obtained to be (58331±71) cm-1 and 0.69, respectively.
Geometrical explanation and application of some algebraic direct methods
Authors: Zhang Shan-Qing  ,   上海交通大学数学系, 上海  200240；杭州电子科技大学图形图像研究所, 杭州  310018
Published: December 2020

Based on the polygons of the differential equation, geometrical explanation for some algebraic direct methods is given, and its generalization of differential system is presented. Finally, the validity of this explanation is illustrated with variant Boussinesq system.
Exact solution of SU(2)-invariant Thirring model with non-diagonal open boundaries
Authors: Tang Mei-Juan  , Wang Yan-Shen  ,   西安交通大学理学院应用物理系，西安  710049
Published: December 2020

The SU(2)-invariant Thirring model with non-diagonal open boundaries in one spatial and one time dimensions is studied in the framework of quantum inverse scattering method. With the help of guage transformation independent of spectral parameter in the auxiliary space, suitable Fock vacuum state is constructed. The eigenvalues and its Bethe Ansatz equations of the transfer matrix are obtained by mean of Bethe Ansatz, and finally the boundary freedom degrees of the system are discussed.
Study on the traffic behavior of on-ramp system with two-lane main road under signal controlling
Authors: Teng Ya-Fan  , Gao Zi-You  , Jia Bin  , Li Feng  ,   北京交通大学交通运输学院，北京  100044
Published: December 2020

In this paper we investigate the two-lane main road on-ramp system with signal-controlling using the cellular automata traffic flow model. The traffic signal is setup at the merging part between the main road and the on-ramp so that it can control the vehicles of both roads. We simulate the effect of traffic signal on vehicle flows of main road and on-ramp, and the traffic capacity and average velocity at the merging part are discussed. Through the analysis of the phase diagram, it can be found that the on-ramp system with two-lane main road can embody more complicated and realistic traffic flow characteristics than the on-ramp system with single-lane main road. Compared with the model introduced by Jiang Rui ［Jiang R 2003 J. Phys. A 36 11713］, the simulation results indicate that the state of traffic flow is improved obviously and the capacity of the on ramp system has increased.
Studied on low-frequency oscillation in the Boost converter with one cycle control
Authors: Wang Fa-Qiang  , Zhang Hao  , Ma Xi-Kui  ,   西安交通大学电气工程学院电力设备电气绝缘国家重点实验室，西安  710049
Published: December 2020

On the assumption that the frequencies of the inductor current and output voltage are much lower than the switching frequency of the converter, the critical condition between the discontinuous conduction mode (DCM) and the continuous conduction mode (CCM) is given, and the transfer function of the closed loop output to the reference voltage under DCM and CCM are derived respectively. The analytical results show that the DC-DC Boost converter can be stable in the state of period 1 in DCM, but it can not be stable in CCM, i.e., the low-frequency oscillation will occur. Further, the frequency of the low-frequency oscillation is calculated by using zero-pole analysis method, and the oscillation amplitude of the output voltage is calculated in terms of the topology of the circuit. Finally, the theoretical results are verified by numerical simulations and circuit experiments.
Adaptive synchronization research on the uncertain complex networks with time-delay
Authors: Luo Qun  , Wu Wei  , Li Li-Xiang  , Yang Yi-Xian  , Peng Hai-Peng  ,   北京邮电大学信息处理与智能技术重点实验室，数字内容研究中心,北京  100876
Published: December 2020

The synchronization problem of uncertain dynamical network model with time-delay nodes has been researched, where the network structure is known or totally unknown. Based on Lyapunov stability theorem, the synchronization controller of complex networks and the adaptive controller of synchronization of complex networks are designed respectively under the circumstances of known parameters and unknown parameters. The sufficient condition of network synchronization is given to guarantee that the dynamical network asymptotically synchronizes at the individual node state in arbitrary specified network. Finally, numerical simulations are provided to verify the effectiveness of the developed methods.
The driving potential and cross sections for synthesizing super heavy nuclei with hot fusion
Authors: Huang Ming-Hui  , Gan Zai-Guo  , Fan Hong-Mei  , Su Peng-Yuan  , Ma Long  , Zhou Xiao-Hong  , Li Jun-Qing  ,   (1)中国科学院近代物理研究所，兰州  730000; (2)中国科学院近代物理研究所，兰州  730000；中国科学院研究生院，北京  100049
Published: December 2020

The dinuclear model of the formation mechanism of a superheavy compound nucleus assumes that when all nucleons of the projectile have been transferred in to the target nucleus the compound nucleus is formed. The nucleon transfer is determined by the driving potential. For some reaction channels, the relation between nucleon transfer and the evolution path of the neutron/proton ratio is rather complicated. In principle, both the dynamical equation and the driving potential should be a two-dimensional explicit function of the neutron and proton. For the sake of simplicity we calculated the driving potential by choosing the path of the nucleon transfer which is related to the nutron/proton ratio, and the calculated evaporation residue cross-sections to synthesize the superheavy nuclei are much closer to the experimental data.
Density functional study of CO adsorption on Pu (100) surface
Authors: Luo Wen-Hua  , Meng Da-Qiao  , Li Gan  , Chen Hu-Chi  ,   表面物理与化学国家重点实验室，绵阳  6219007
Published: December 2020

The adsorption of CO on Pu (100) surface were studied by the density functional theory (DFT). The calculation results show that the O-down adsorption is less stable than the C-down adsorption which is found to be a strong chemisorption. The stability of adsorption configuration of CO is hollow tilted > hollow vertical > bridge > on-top. The interaction between Pu atom and CO molecule results mainly from the contribution of hybridized molecular orbital of CO molecule and hybridized orbital of surface Pu atom. A small activation barrier of 0.280eV is found for the dissociation of CO molecule in hollow tilted configuration, which indicates the dissociative adsorption of CO on Pu (100) surface at the lower temperature with dissociated C and O atoms favoring the hollow site of lowest energy.
Electric quadrupole transitions of K-like ions (Z=22—42)
Authors: Yang Fu-Li  , Yi You-Gen  ,   (1)西藏大学农牧学院,西藏  860000; (2)中南大学物理科学与技术学院，长沙  410083
Published: December 2020

A fully relativistic multiconfiguration Dirac-Fock method with Breit and QED corrections is used to calculate the 4s 2S─3d 2D(Z=22—42)transition energy level separations, transition probabilities and oscillator strengths for the K-like ions. In the calculation, we have considered the significant Breit and QED corrections. The results are in good agreements with recent experimental data and other theoretical values. The results show that the electric quadrupole transition probabilities are in correspondence with these of E1 transitions and can not be ignored in the laser plasma of high temperature in ICF and MCF Fusion.
A modification method of additivity rule for total cross section calculations of electron scattering from molecules considering the geometric shielding effect
Authors: Shi De-Heng  , Sun Jin-Feng  , Zhu Zun-Lüe  , Liu Yu-Fang  ,   (1)河南师范大学物理与信息工程学院,新乡  453007; (2)信阳师范学院物理电子工程学院,信阳  464000;河南师范大学物理与信息工程学院,新乡  453007
Published: December 2020

Taking into consideration the changes of the geometric shielding effect in a molecule as the incident electron energy varies, a modification method of additivity rule model for total cross section calculations of electron scattering from molecules at intermediate and high energies, is presented. Employing the modified additivity rule model, the total cross sections for electron scattering from NO, N2O, NO2 and C2H6 are calculated over a wide energy range from 50 to 5000 eV by using the experimental results of electron scattering from atoms C, N, H and O. The calculated values of total cross sections are compared with those obtained by measurements and other theories wherever available, and good agreement is attained over a wide energy range. It is shown that the total cross sections obtained by the modified additivity rule model are much closer to the measurements than the unmodified one and other theories. And it is also shown that the modification of complex optical potential must be related with energy of incident electrons so that the potential for total cross section calculations of electron scattering from free atoms is made suitable for the total cross section calculations of electron scattering from the ones in the molecule.
The dynamics of bubbles
Authors: Zhang A-Man  , Yao Xiong_Liang  , Li Jia  ,   哈尔滨工程大学船舶工程学院，哈尔滨  150001
Published: December 2020

The fluid is assumed to be inviscid and incompressible and the flow irrotational. The three_dimensional numerical model is established to simulate the interaction of multiple bubbles and the fast Fourier transform on multipoles (FFTM) method is combined with the higher order boundary method (BEM) to study the physics of multiple bubble dynamics. FFTM method is employed to speedup the solution of the boundary integral equation while achieving the same order of accuracy, enabling to simulate the dynamics of multiple bubbles in a reasonable time. Elastic mesh technique (EMT), which is a new mesh regulation technique, is applied to maintain the regularity of the triangular element mesh used to discretize the dynamic boundary surface during the evolution of bubbles. All these measures make the present approach viable and robust, which is validated by computations of several bubble dynamics problems. Numerical analysi was carried out for the interaction of multiple bubbles and the bubble dynamics. Some physical behaviors of the multiple bubbles are presented in this work. The factors affecting the expansion, collapse, moving of multiple bubbles and the jet formation are also discussed.
First-principles research on the effect of high oxygen vacancy concentration in anatase TiO2 on Mott phase transition， absorption spectrum Einstein shift and life_time of electrons
Authors: Hou Qing-Yu  , Zhang Yue  , Zhang Tao  ,   北京航空航天大学材料科学与工程学院，北京  100083
Published: December 2020

Based on the study of density function using first-principles theory，by studying the concentration of oxygen vacancies，the DOS and the absorption spectrum of anatase，we discovered that the high concentration of oxygen vacancies has great influence on the forbidden band gap，absorption spectrum Einstein shift and life_time of electrons，and explained the reason why the concentration of oxygen vacancy makes the forbidden band gap to narrow. At the same time，the anatase semiconductor has Mott transition when there is a high concentration of oxygen vacancies. The conclusion that suitably controlling the concentration of oxygen vacancy leads to Einstein shift is deduced by comparing the Einstein shift experiment of oxygen vacancies in anatase with that in the plasma. It offered credible data for preparation visible light activator suitably by controlling the concentration of oxygen vacancies in anatase.
Optical properties of InGaAs/GaAs quantum chains
Authors: Wang Bao-Rui  , Sun Zheng  , Xu Zhong-Ying  , Sun Bao-Quan  , Ji Yang  , Z. M. Wang  , G. J. Salamo  ,   (1)Department of Physics，University of Arkansas; (2)中科院半导体研究所，超晶格国家重点实验室，北京  100083
Published: December 2020

We have investigated the steady-state and transient optical properties of InGaAs/GaAs quantum chains and found that the photoluminescence (PL) decay time exhibits a strong photon energy dependence. It increases with the decrease of the emission energy. It is also found that the PL decay time increases with the excitation power. When the excitation power is large enough the PL decay time tends to be saturated. All these experimental results show that there is a strong carrier coupling along the chain direction in the quantum dot chain structure. The polarization PL measurements further confirm the carrier transfer process along the chain direction.
Study on the mechanical properties of diamond like carbon films with Si doping
Authors: Zhao Dong-Cai  , Ren Ni  , Ma Zhan-Ji  , Qiu Jia-Wen  , Xiao Geng-Jie  , Wu Sheng-Hu  ,   兰州物理研究所表面工程技术国家重点实验室，兰州  730000
Published: December 2020

A series of samples with different Si concentration were prepared by adjusting the numbers of Si-doped graphite targets and pure graphite targets. It was found that the stress in the thin films decreased from 4.5GPa to 3.1GPa when the Si concentration reached 6.7at.%，but the hardness kept constant at about 3600Hv，almost the same as of un-doped thin films，and the friction coefficient of thin films kept constant at about 0.15. As the Si concentration in the thin film kept on increasing，the concentration of C-Si bond will increase，leading to the decrease of hardness and stress and the increase of friction coefficient.
Exact solutions of Gerdjikov-Ivanov equation
Authors: Li Xiang-Zheng  , Li Xiu-Yong  , Zhao Li-Ying  , Zhang Jin-Liang  ,   河南科技大学理学院，洛阳  471003
Published: December 2020

The Gerdjikov-Ivanov equation which appears，in the fields of quanta field theory，weak nonlinear dispersive water wave，nonlinear optics， etc.， has been discussed. Nonlinear mathematical physics equation with higher order nonlinear terms is educed in the discussion of Gerdjikov-Ivanov equation. The Liénard equation is chosen as subsidiary ordinary differential equation, with the help of which and according to homogeneous balance principle，the Gerdjikov-Ivanov equation has been solved，and the envelope solitary wave solutions and envelope sinusoidal wave solutions have been obtained.
A new method of weak signal detection using Duffing oscillator and its simulation research
Authors: Wang Yong-Sheng  , Jiang Wen-Zhi  , Zhao Jian-Jun  , Fan Hong-Da  ,   海军航空工程学院兵器科学与技术系，烟台  264001
Published: December 2020

The theory and simulation technique of weak signal detection using chaos state phase change is researched in this paper. The method of weak signal detection by using the Duffing oscillator's initial conditions sensitivity was firstly analyzed， the existing transition process would affect the detection capability. Then an improved method was presented. In order to compare these two methods， the input pseudo-noise expression and the calculating step selection in simulation were researched， and the simulation models were established. The new method was shown to have better capability through analyzing the signal detection experimental results under the condition of typical noise intensity background. The experiments showed that the Duffing oscillator in special critical chaos state is also sensitive to noise， which leads to the difficulty in exactly deciding the minimal detection limit by phase change， and the limitation of the phase change method was discussed.
Structure and analytic potential energy functions of the molecules AlO2 and Al2O
Authors: Lü Bing  , Linghu Rong-Feng  , Zhou Xun  , Cheng Xin-Lu  , Yang Xiang-Dong  ,   (1)贵州师范大学理学院,贵阳  550001; (2)贵州师范大学理学院,贵阳  550001；四川大学原子与分子物理研究所,成都  610065; (3)四川大学原子与分子物理研究所,成都  610065
Published: December 2020

The density function (B3LYP) method has been used to optimize the possible ground-state structures of AlO2 and Al2O molecules. The results show that the ground state of AlO2 molecule has D∞h symmetry and is in the X2Πu state. The parameters of structure are RAl-O=0.1661 nm and De=8.9217eV, respectively. The results also show that the ground state of Al2O molecule has D∞h symmetry and is in the X1Σg state. The parameters of structure are RO-Al=0.1731 nm and De=10.5269eV, respectively. The potential energy functions of AlO2 and Al2O have been derived from the many-body expansion theory. The contours describe correctly the configurations and the dissociation energies of the two ground-state molecules.
Quantum key distribution using binary-modulated coherent states
Authors: He Guang-Qiang  , Guo Hong-Bin  , Li Yu-Dan  , Zhu Si-Wei  , Zeng Gui-Hua  ,   上海交通大学电子工程系，区域光纤通信网与新型光通信系统国家重点实验室，上海  200240
Published: December 2020

A quantum key distribution (QKD) scheme using binary-modulated coherent states is proposed in this paper. Compared with Gaussian sources of QKD using Gaussian-modulated coherent states, the binary sources of the proposed scheme are the simplest sources, and the binary modulation is the most usual modulation format in the digital optical-fiber communication. The security of the proposed schemeagainst beam splitter attack is analyzed using Shannon information theory. The analytical expression of the secret information rate is given in terms of modulation-demodulation parameters and channel parameters. The quantum noise of coherent states guarantees the security of the proposed scheme.
The left-handedness effect of quantum manipulation in medium
Authors: Zeng Fu-Hua  , Liu Zheng-Dong  , Zheng Jun  , Fang Hui-Juan  ,   (1)南昌大学近代物理研究所，南昌  330031；南昌大学纳米技术工程研究中心，南昌  330047; (2)南昌大学近代物理研究所，南昌  330031；南昌大学纳米技术工程研究中心，南昌  330047；南昌大学材料科学与工程学院，南昌  330031
Published: December 2020

The quantum mechanics system with interaction between quasi-Λ type four-level atoms and multi-mode light fields is discussed. Under the mechanism of quantum interference, the relative dielectric permittivity and the relative magnetic permeability will change remarkably. In certain range of parameters, both of them will be negative. At this time, the left-handedness effect happens.
Spectral switches and effect in singular optics with polychromatic light field
Authors: Zhao Guang-Pu  , Lü Bai-Da  ,   (1)四川大学激光物理与化学研究所，成都  610064; (2)宜宾学院计算物理重点实验室，宜宾  644007；四川大学激光物理与化学研究所，成都  610064
Published: December 2020

The expression for the spectral density of polychromatic Gaussian and Gaussian-Schell model (GSM) beams propagating through double slits in Young's experiment are derived, which enables us to study the behavior of spectral switches in Young's experiment illuminated by fully and partially coherent polychromatic light beams and to judge if their spectral switches belong to the effect in singular optics. It is shown that the criterion for the effect in singular optics with polychromatic light field should be Smin=0 (Smin is the minimum of the spectral density at spectral switches) rather than Imin=0 (Imin is the minimum of the total intensity). In Young's experiment illuminated by polychromatic GSM beams the spectral switches in both near and far zones are not attributed to the effect in singular optics because Smin≠0. If the double slits in Young’s experiment are illuminated by polychromatic Gaussian beam, the spectral switches in the far zone belong to the effect in singular optics, whereas it is not the case in the near zone.
Mechanism of E′ center formed by irradiation with high energy particles in silica glasses
Authors: Xiao Zhong-Yin  , Wang Ting-Yun  , Luo Wen-Yun  , Wang Zi-Hua  ,   上海大学通信与信息工程学院,上海  200072；上海大学特种光纤与光接入网教育部重点实验室，上海  200072
Published: December 2020

In this paper, a kinetic model for the radiation-induced production of the intrinsic point defect E′ center is proposed. The relation of E′ center concentration changing with dose is obtained. The results show that the production of E′ center includes two processes, i.e. the creation of new defects and the activation of preexisting defects. The stained bonds (or oxygen replacement) in silica networks lead to the creation of new defects, whose concentration increases linearly with the dose. The preexisting defects produce the activation, which tends to saturation. The theoretical result is in good agreement with the experiment.
Radiation mechanism of pulsed laser ablation of metal Al
Authors: Huang Qing-Ju  ,   茂名学院物理系,茂名  525000
Published: December 2020

Time-resolved measurement of plasma emission spectra by pulsed XeCl excimer laser ablation of Al under different conditions is reported. The experimental results show that plasma emission spectra are composed of atomic spectrum, univalent ion spectrum and continuous radiation. The atomic spectrum intensity and duration is most significant, the next is the univalent ion spectrum, the continuous radiation is weakest. The detailed mechanism of species excitation is discussed. The continuum radiation comes from electron bremsstrahlung and recombination of electron and ion, the primary atomic and univalent ion excitation originate from recombination of ion and electron. The experimental results are qualitatively explained with the mechanism.
The study of nonlinear waves in plasma containing both positively and negatively charged ions
Authors: He Guang-Jun  , Tian Duo-Xiang  , Lin Mai-Mai  , Duan Wen-Shan  ,   西北师范大学物理与电子工程学院，兰州  730070
Published: December 2020

Zakharov-Kuznetsov(ZK) equation, modified ZK equation and coupled ZK equation are derived for magnetized plasma containing both positively and negatively charged cold ions and hot electron by using the reductive perturbation method in this paper. We obtain a solitary wave solution, and also obtain the variation of solitary wave parameters, such as amplitude, width, velocity of soliton, with the mass ratio of negative ions to positive ions, the negatively charged ion number density and the magnetic field intensity.
Characterization of Hall-Petch relation on microstructural parameter of softer sublayer and the hardness in nanomultilayers
Authors: Liu Ming-Xia  , Huang Ping  , Zhang Jian-Min  , Xu Ke-Wei  ,   (1)陕西师范大学物理学与信息技术学院，西安  710062; (2)西安交通大学金属材料强度国家重点实验室，西安  710049
Published: December 2020

Scale dependent microstructures and plastic deformation in Ni/Al nanomultilayers with different modulated ratio has been investigated as a function of bilayer thickness by X-ray diffraction and nanoindentation. Experimental results show that the hardness and the related microstructural parameter in the softer sublayer exhibited the similar variation tendency, which indicated the sensitivity of plastic behaviors on the microstructural constraints in softer sublayer. Further investigation showed that in the nanometer regime, by adopting a new parameter r in softer sublayer (r=Lsub/d, where Lsub is the sublayer thickness and d is the grain size), the competing grain-boundary and interface-boundary strengthening mechanisms could be unified. Moreover, within the overall scale, the deformation of nanomultilayers could follow the Hall-Petch relation with decreasing characteristic length scales.
Influence of structure and doping concentration of AlxGa1-xN/GaN double quantum wells on wavelength and absorption coefficient of intersubband transitions
Authors: Lei Shuang-Ying  , Shen Bo  , Zhang Guo-Yi  ,   (1)北京大学物理学院,介观物理国家重点实验室，北京  100871; (2)东南大学微电子机械系统教育部重点实验室，南京  210096
Published: December 2020

By solving the Schrdinger and Poisson equations self-consistently, the central barrier height, central barrier width, well width, and doping concentration in the barriers of symmetric Al0.75Ga0.25N/GaN double quantum wells (DQWs) have been studied to investigate their influences on the wavelength and absorption coefficient of intersubband transitions (ISBTs). A smaller wavelength of the ISBT between the first odd and the second even order subbands (S1odd-S2even ISBT) in Al0.75Ga0.25N/GaN DQWs and a larger absorption coefficient of the S1odd-S2even ISBT were obtained with decreased central barrier height, when the central barrier height was larger than 0.62 eV. The wavelength of the S1odd-S2even ISBT decreases, and the absorption coefficient of the S1odd-S2even ISBT increases, when the width of the central barrier is reduced. On the other hand, decreasing the width of the well will result in smaller wavelength of the S1odd-S2even ISBT and larger absorption coefficient of the S1odd-S2even ISBT when the width of the well is narrower than 1.9 nm. When doping concentration in the barriers is smaller than 1018/cm3， the wavelength of the S1odd-S2even ISBT is unchanged, while the absorption coefficient of the S1odd-S2even ISBT increases with the doping concentration. These results provide useful guidance for realization of ultrafast two-color optoelectronic devices operating in the optical communication wavelength range.
Asymmetric Kondo resonance splitting transition in T-shaped coupled-quantum-dot devices
Authors: Chen Xiong-Wen  , Shi Zhen-Gang  , Chen Bao-Ju  , Song Ke-Hui  ,   (1)怀化学院物理与电子信息科学系，怀化  418008; (2)怀化学院物理与电子信息科学系，怀化  418008；怀化学院信息科学研究所，怀化  418008
Published: December 2020

Using the slave-boson mean-field approximation, we theoretically study the transport properties of the ground state of the T-shaped coupled quantum dots with two metallic leads by means of one-impurity Anderson Hamiltonian. It is found that when this system is in the equilibrium state, with the increase of the inter-dot coupling, the Kondo resonance is suppressed, and the single Kondo peak of the density of the Kondo quantum dot is split into two asymmetric Kondo peaks. When it is in the non-equilibrium state, when increasing the bias, this asymmetric Kondo splitting is enhanced.
Monte Carlo simulation of shot noise in the coherent and mesoscopic system
Authors: Chen Hua  , Du Lei  , Zhuang Yi-Qi  ,   (1)西安电子科技大学技术物理学院，西安  710071; (2)西安电子科技大学微电子学院，西安  710071
Published: December 2020

According to the conclusion that the charge which passes through a low-temperature quantum conductor over fixed time has a binomial distribution, a shot noise model based on the physical implication of Landauer formula in the coherent and mesoscopic system is built, and time sequences of shot noise are produced by the Monte Carlo methods. It is well known that shot noise suppression in mesoscopic systems originates from the correlation in electron transport, and the bimodal probability distribution of the transmission eigenvalues in quantum chaos cavity and disordered metal leads to shot noise suppression, from which it is possible to correlate the distribution of the transmission eigenvalues and the correlation in electron transport.
Study of synthetic antiferromagnetic Ni81Fe19/Co90Fe10/Ru/Co90Fe10/Ni81Fe19
Authors: Yang Shu-Ke  , Bao Jin  , Su Xi-Ping  , Xu Xiao-Guang  , Jiang Yong  ,   北京科技大学材料物理与化学系，新金属材料国家重点实验室，北京  100083
Published: December 2020

A series of synthetic antiferromagnets and spin valves with synthetic antiferrimagnets as free layers were fabricated by DC magnetron sputtering. It is found that inserting a thin Co90Fe10 layer of proper thickness between Ni81Fe19 and Cu is an effective means to strengthen the antiferromagnetic coupling in the synthetic antiferrimagnet, and obtain synthetic antiferromagnets with excellent magnetic properties, i.e., higher saturation magnetic field, lower saturation magnetization value and better thermal stability. In addition, spin valves using the synthetic antiferrimagnet as a free layer have better stability.
Soft magnetic properties and microwave permeability of multilayer nanogranular films with high resistivity
Authors: Bie Shao-Wei  , Jiang Jian-Jun  , Ma Qiang  , Du Gang  , Yuan Lin  , Di Yong-Jiang  , Feng Ze-Kun  , He Hua-Hui  ,   华中科技大学电子科学与技术系，武汉  430074
Published: December 2020

The resistivity, soft magnetic properties and microwave permeability of multilayer nanogranular films suitable for high frequency applications have been investigated in this work. These films were prepared by repeated sequential depositions of thin layers of Co40Fe40B20 and SiO2. After vacuum annealing at 250℃ under a uniform in-plane magnetic field of 100kA/m for 2h, the Co40Fe40B20/SiO2 multilayer films have the hard axis coercivity of 210A/m, saturation magnetization of 838.75kA/m, resistivity of 2.06×103μΩcm. Moreover, the results show that the films have an in-plane uniaxial anisotropy of 2.78kA/m. As a consequence, the real part of measured permeability keeps constant at 125 up to 1.6GHz. The resonance frequency was about1.73GHz.
The dynamic reliability of ultra-thin gate oxide and its breakdown characteristics
Authors: Luan Su-Zhen  , Liu Hong-Xia  , Jia Ren-Xu  ,   西安电子科技大学微电子学院,宽禁带半导体材料与器件教育部重点实验室，西安  710071
Published: December 2020

The experiment result shows that under unipolar voltage stress, electrons tunneling into ultra-thin gate oxide during on-time will recombine with the trapped holes, and neutral electron traps would be generated. These electron traps would assist electrons tunneling into gate oxide. It is proposed that the characteristic time τ for the charge to be trapped in SiO2 is longer than the on-time ton of unipolar stress. During the on-time few charges are trapped and during the off-time some trapped charges will be detrapped, thus very few neutral electron traps are generated. With the stress time increasing, the density of neutral electron traps would reach a critical value, and then the gate oxide would break down abruptly. The increase in unipolar breakdown time tBD is attributed to fewer charge trapping during the on-time and charge detrapping during the off-time.
Study of optical properties of nano-scale ZnO and ZnO-SiO2 thin films
Authors: Yuan Ning-Yi  , He Ze-Jun  , Zhao Chang-Ning  , Li Feng  , Zhou Yi  , Li Jin-Hua  ,   江苏工业学院数理学院，常州  213164
Published: December 2020

ZnO and ZnO-SiO2 nano-scale thin films were deposited on glass substrates by the sol-gel method. The ultraviolet(UV)-visible spectrophotometer was used to analyze their optical properties. The UV-visible transmittance spectra of ZnO films showed that when the mole concentration of ZnO precursor decreased from 0.7 to 0.06 mol/L, besides the absorption edge at 380 nm, a new absorption edge around 320 nm appeared. Furthermore the decrease of mole concentration of ZnO precursor improved the transmittance in the range between 380 and 320 nm. However, ZnO-SiO2 nano-scale thin films only have one absorption edge at 310nm. The optical band gap of ZnO was enlarged when deposited in SiO2 matrix.
Entropy of the scalar field in general accelerating non-stationary black holes with electric charge and magnetic charge
Authors: Yang Bo  ,   重庆三峡学院物理与电子工程学院,重庆  404000
Published: December 2020

Using tortoise coordinate transformation, Klein-Gordon field equation is simplified and thermal radiation temperature near the event horizon is obtained. Meanwhile, adopting thin film brick-wall model and regulating the cut-off parameter and the thin film's thickness properly, the entropy of thin film near the event horizon is acquired. The results show that the entropy of the black hole is proportional to the area of the event horizon.
The dual-resonance characteristic of coupled bistable system affected by two-frequency signal
Authors: Lin Min  , Fang Li-Min  , Zhu Ruo-Gu  ,   中国计量学院计量技术工程学院，杭州  310018
Published: December 2020

Two single bistable systems were constituted into a coupling system by means of nonlinear coupling. One of the bistable systems was considered as controlled system with fixed parameters, and the other as control system with adjustable parameters. Adjusting the coupling coefficients and parameters of the control system can produce stochastic resonance. With a single-frequency signal added to the control system, changing the signal frequency can produce the resonance. Due to the effect of coupling, the resonance of control system will affect the stochastic resonance of the controlled system, and the dual-resonance phenomenon happens in the coupled system, which realizes the usage of one resonance to influence another and make the stochastic resonance of controlled system more intense. This also has been verified using computer simulation.
Parametric equations and its first integrals for Birkhoffian systems in the event space
Authors: Zhang Yi  ,   苏州科技学院土木工程学院，苏州  215011
Published: December 2020

In this paper, the dynamics of Birkhoffian systems in the event space is studied. The Pfaff-Birkhoff-d'Alembert principle and Birkhoff's parametric equations for the Birkhoffian systems are established in the event space of (2n+1) dimensions. The first integrals of the parametric equations and the conditions for their existence are presented.
The entanglement in one-dimensional random XY spin chain with Dzyaloshinskii-Moriya interaction
Authors: Shan Chuan-Jia  , Cheng Wei-Wen  , Liu Tang-Kun  , Huang Yan-Xia  , Li Hong  ,   湖北师范学院物理系，黄石  435002
Published: December 2020

In this paper, the entanglement in one-dimensional random XY spin system with Dzyaloshinskii-Moriya interaction is investigated, for which the impurities of exchange couplings and the external magnetic fields are considered as random Gaussian distribution variables. By solving the different spin-spin correlation functions and the average magnetization per spin, the concurrence is found. The results show that the Gaussian distribution and Dzyaloshinskii-Moriya interaction have considerable effect on the entanglement near particular locations of the system. Moreover, the entanglement can be controlled and enhanced by varying the distributions of the impurities, the strength of external magnetic field and Dzyaloshinskii-Moriya interaction.
A digital watermarking algorithm based on chaos and fractional Fourier transformation
Authors: Zou Lu-Juan  , Wang Bo  , Feng Jiu-Chao  ,   华南理工大学电子与信息学院，广州  510641
Published: December 2020

Based on chaotic sequences and discrete fractional Fourier transform, a digital watermarking algorithm is proposed, and its resistance to attacks is simulated. The results show that the algorithm is easy to realize, and is robust to the attacks from JPEG compression, noise perturbation and filtering.
Research of fine structure and universal constants of bifurcation in converters
Authors: Yang Ru  , Zhang Bo  , Chu Li-Li  ,   (1)广州大学物理与电子工程学院，广州  510400; (2)华南理工大学电力学院，广州  510640
Published: December 2020

The fine structure and scaling invariability of bifurcation in converters is discussed. Universal constants of converters of one and two dimensions and chaos combination belts have been obtained by numerical simulation. Spectrum structure is used to estimate the system behavior and reveal the structure of solution in the converter. The structure of spectrum also validates the fine structure of bifurcation in the converter. Experiment results illustrate the process of bifurcation to chaos and validate the simulation results.
Study on intrinsic optical bistability in Tm-doped laser crystal pumped at 648nm avalanche wavelength
Authors: Li Li  , Zhang Xin-Lu  , Chen Li-Xue  ,   (1)哈尔滨工程大学理学院，哈尔滨  150001; (2)哈尔滨工业大学物理系，哈尔滨  150001; (3)哈尔滨工业大学物理系，哈尔滨  150001;哈尔滨工程大学理学院，哈尔滨  150001
Published: December 2020

Intrinsic optical bistability (IOB) in Tm-doped laser crystal pumped at 648nm avalanche wavelength is predicted theoretically and studied numerically. Based on the theory of nonlinear rate equations, the analytical formula of avalanche threshold condition is deduced in the steady-state approximation. Transient response of photon avalanche, IOB and influence of system parameters on IOB are studied numerically. The numerical simulation shows that IOB of 2μm fluorescence emission in Tm-doped laser crystal can be experimentally observed. Controllable bistable hysteresis loop can be achieved by adjusting experimentally adjustable parameters.
Studies on dual-core-bidirectional optical fiber chaotic secure communication system
Authors: Yan  Sen-Lin  ,   南京晓庄学院物理系，南京  210017
Published: December 2020

A dual-core-bidirectional optical fiber chaotic secure communication system is proposed based on coupling-feedback synchronization of chaotic injected multi-quantum well (MQW) laser systems with fiber channels for optical fiber secure communications. A physical model of the system is built using dual-core optical fiber connecting the transmitter and receiver. Chaotic synchronization was theoretically and numerically studied and we found theoretically that self-phase modulation in the fiber would limit the chaotic synchronization. The nonlinear phase shift, power limit and propagation length are formulated. Chaotic synchronization of two long-distance fibers was numerically achieved, and synchronization time varying with fiber propagation length was numerically analysed. Optical fiber chaotic communications and their synchronization errors were numerically simulated in long-distance dual-core-bidirectiond optical fiber chaotic secure communications with an analog signal of modulation frequency 06 GHz, a digital signal of modulation rate 06 bit/s and a bit rate of 005 Gbit/s of chaos keying shift, respectively. The system bandwidth is also numerically analysed. The system has a good security capability of application in dual-core-bidirectional fiber secure communications.
Interactions between strong nonlocal optical spatial solitons in nematic liquid crystals
Authors: Yang Ping-Bao  , Cao Long-Gui  , Hu Wei  , Zhu Ye-Qing  , Guo Qi  , Yang Xiang-Bo  ,   (1)华南师范大学光子信息技术广东省高校重点实验室，广州  510006; (2)华南师范大学激光生命科学研究所，广州  510631
Published: December 2020

In this paper, we investigate the interactions between optical spatial solitons in nematic liquid crystals (NLC) with numerical simulations and experiments. The response function is exponential-decay function in NLC, which is different from the Snyder-Mitchell model. Through numerical simulations, we discovered that the crosspoint of soliton interaction is in inverse proportion to the square root of injection power in NLC . We also found that the position of crosspoint is independent of the distance between solitons in strong nonlocal Gauss function response, but it is not the same with exponential-decay function in NLC. Through experiments,we found the positions of crosspoint is in inverse proportion to the square root of inject power,it is also related to the critical power of solition formation and the distance between solitons.
Soft X-ray magmeto-optical Faraday rotation measurements with the multilayer polarizer
Authors: Yan Fen  , Cui Ming-Qi  , Chen Kai  , Sun Li-Juan  , Xi Shi-Bo  , Zhou Ke-Jin  , Zheng Lei  , Zhao Yi-Dong  , Wang Zhan-Shan  , Zhu Jing-Tao  , Zhang Zhong  , Zhao Jia  ,   (1)北京工商大学，北京  100037; (2)同济大学精密光学工程技术研究所，物理系，上海  200092; (3)中国科学院高能物理研究所，北京  100049
Published: December 2020

We measured magneto-optical (MO) Faraday rotation around the M2,3 edges (60—70 eV) of Ni film on 3W1B beam line of Beijing Synchrotron Radiation Facility (BSRF) in the soft X-ray region through a versatile polarimeter with mutilayer polarizers, which is mainly composed of polarizer, analyzer, sample frame, round NdFeB permanent-magnet and MCP detector. We used the reflective aperiodic molybdenum/silicon broadband multilayer polarizers as the polarizer and the analyzer in the versatile polarimeter, and obtained a series of Faraday rotation results in the 60—70 eV region. The results demonstrate that the Faraday rotation angles are obviously large around Ni M2,3 edges, the rotation angles are 179±019°(average rotation angle in parallel and antiparallel magnet fields) and -076±009°(average rotation angle in parallel and antiparallel magnet fields) at the energy 655 eV and 68 eV, respectively.
The extraction method for trap parameters in 4H-SiC MESFETs
Authors: Lü Hong-Liang  , Zhang Yi-Men  , Zhang Yu-Ming  , Che Yong  , Wang Yue-Hu  , Chen Liang  ,   (1)武警工程学院军械运输系，西安  710086; (2)西安电子科技大学微电子学院，教育部宽禁带半导体重点实验室，西安  710071
Published: December 2020

The small signal equivalent circuit of SiC MESFETs has been studied and the parasitic and intrinsic elements have been extracted with both numerical and analytical methods. The trapping-emission mechanism is discussed in detail. The proposed model is valuable for the optimization of the device design and processing.