bluuebunny/crossref_metadata_2025 huggingface dataset:
Theoretical investigation on dispersion effect and two-photon resonance enhancement of molecular first hyperpolarizability
Authors: Li Hai-Peng  , Han Kui  , Lu Zhen-Ping  , Shen Xiao-Peng  , Huang Zhi-Min  , Zhang Wen-Tao  , Bai Lei  ,   中国矿业大学理学院，徐州  221008
Published: December 2020

The calculations of the first hyperpolarizability frequency dispersion effect of hemicyanine derivative chromophore have been performed employing time-dependent Hartree-Fock and sum-over-states method respectively. Two-photon resonance enhancement characteristics of second harmonic generation β(-2ω；ω，ω) have also been investigated using the two-level model (TLM), which was originated by Ouder and Chemla. The results indicate that the first excited state dominates the nonlinear optical properties of hemicyanine derivatives. The first hyperpolarizability β(-2ω；ω，ω) increases with the decrease of fundamental wavelength and gives rise to two-photon resonance near the fundamental wavelength of 950 nm, in accordance with the known experimental facts. In addition, the relaxation effect of the excited states should be considered for TLM in the resonance regime. These researches provide theoretical references for experimental measurements.
Comparison of accuracy between two spectral phase interferometric methods in the characterization of complex pulses
Authors: Wen Jin-Hui  , Lei Liang  , Jiao Zhong-Xing  , Lai Tian-Shu  , Lin Wei-Zhu  ,   中山大学物理系，光电材料与技术国家重点实验室，广州  510275
Published: December 2020

By means of numerical simulation, a comparison is made between conventional spectral phase interferometry for direct electric -field reconstruction (SPIDER) and delay-controlled fringe-free SPIDER (DCFF-SPIDER) in the accuracy of characterization of complex pulses. The results show that errors occur likely when complex pulses with abrupt variations in spectra or/and phases are characterized with conventional SPIDER, while DCFF-SPIDER can give high accuracy. The underlying reasons for this difference are discussed.
Optimum realization of the EPR paradox in the non-degenerate parametric amplification system
Authors: Zhao Chao-Ying  , Tan Wei-Han  ,   上海大学物理系,上海  200444
Published: December 2020

In this paper, we use the solution of the Fokker-Planck equation for non-degenerate parametric amplification to deduce the condition of demonstration of the EPR paradox. The numerical simulation shows that the optimum realization of EPR paradox can be achieved by adjusting the degree of squeezing, and this is the best condition for demonstrating the EPR paradox for a given finite loss k.
The influence of shape and atomicity on the surface energy of nanocrystal
Authors: Zheng Rui-Lun  , Tao Ye  ,   (1)涪陵师范学院物理系，重庆  708003; (2)西南大学物理学院，重庆  400715
Published: December 2020

The relation of Debye temperature with the interaction potential of atoms, the r elation of the mean coordination number with the shape and atomicity are deduce d. Through applying the theory of statistical physics, the variation law of the surface energy of rectangular nanocrystals along with the temperature, atomicit y and shape is obtained, and taking Ar nanocrystal as an example, the influence of shape and atomicity on the surface energy of the nanocrystal is discussed.
Blue and white organic light emitting diodes based on a new stilbene derivative dopant
Authors: Wei Fu-Xiang  , Cao Jin  , Zhang Xiao-Bo  , Liu 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

In this paper the electroluminescene of highly efficient blue dopant EBDP was in vestigated. The blue and white organic light emitting diodes with the structure: indium-tin oxide(ITO)/ copper phthalocyanine(CuPc)/N,N′-bis-(1-naphenyl)-N,N′ -biphenyl -1,1′-bipheny1-4-4′-diamine (NPB)/2-t-butyl-9,10-di-(2-naphthyl)anth racene(TBADN):EBDP/tris(8-hydroxyquinoline) aluminum(Alq3)/LiF/Al and ITO/CuPc/NPB/TBADN:EBDP: 4-(dicyanomethylene)-2-t-butyl-6-(1,1,7,7-tetramethylj ulolidyl-9-enyl)-4H-pyran/Alq3/LiF/Al were studied by using EBDP as b lue dopant. For the blue device, the maximum luminance was 26961cd/m2 , and its maximum efficiency was 8.29cd/A. The luminance at a current density 20 mA/cm2 was 1597cd/m2. For the white device, the maximum lu minance 32291cd/m2 and maximum efficiency 8.31cd/A,the luminance of 1 413cd/m2 at a current density 20mA/cm2 were obtained. The slow decrease of efficiency with the increase of current density indicates weak exciton-exciton annihilation, which results from the large steric hindrance due to a non-planar structure of the fluorescence dye EBDP.
Influence of cataphoresis on metal vapor distribution in high repetition rate pulsed discharge metal vapor lasers
Authors: Xia Ting-Ting  , Zhong Jian-Wei  , Mao Bang-Ning  , Chen Gang  , Yao Zhi-Xin  , Pan Bai-Liang  ,   浙江大学物理系，杭州  310027
Published: December 2020

A theoretic model has been established to describe the cataphoresis dynamics in high repetition rate (HRR) pulsed discharge metal vapor lasers (MVLs). The analytic solutions for transient and steady-state diffusion equations of metal vapor concentration are obtained. The axial distribution processes of metal vapors in HRR pulsed discharge He-Sr+ and He-Cd+ lasers have been calculated. It shows that the axial metal vapor distribution between the metal source and the cathode reaches sufficient homogeneity in about 2s, thus ensuring the stable output characteristics of cataphoresis MVLs.
Electron transport through a quantum dot ring
Authors: Deng Yu-Xiang  , Yan Xiao-Hong  , Tang Na-Si  ,   (1)南京航空航天大学理学院，南京  210016; (2)湘潭大学材料与光电物理学院，湘潭  411105
Published: December 2020

Based on the non-equilibrium Green function formalism, we studied the coherent t ransport through a quantum dot ring. Compared with a one-dimensional quantum dot array, a quantum dot ring presents a number of new quasi-bounding-states in its electronic spectra. Moreover, the enhancement of the inter-dot coupling would l ead to the prominent decoherence of Coulomb-blockade conductance oscillation.
Magneto-transport characteristics of two-dimensional electron gas for Si δ-doped InAlAs/InGaAs single quantum well
Authors: Zhou Wen-Zheng  , Yao Wei  , Zhu Bo  , Qiu Zhi-Jun  , Guo Shao-Ling  , Lin Tie  , Cui Li-Jie  , Gui Yong-Sheng  , Chu Jun-Hao  ,   (1)中国科学院半导体研究所，北京  100083; (2)中国科学院上海技术物理研究所红外物理国家重点实验室，上海  200083; (3)中国科学院上海技术物理研究所红外物理国家重点实验室，上海  200083;广西大学物理科学与工程技术学院，南宁  530004
Published: December 2020

Magneto-transport measurements have been carried out on a Si heavily δ-doped In 0.52Al0.48As/In0.53Ga0.47As single q uantum well in the temperature range between 1.5 and 60K under magnetic field up to 10T. We studied the Shubnikov-de Haas(SdH) effect and the Hall effect for th e In0.52Al0.48As/In0.53Ga0.47As sing le quantum well occupied by two subbands，and have obtained the electron concent ration, mobility, effective mass and energy levels respectively. The electron co ncentrations of the two subbands derived from mobility spectrum combined with mu lti-carrier fitting analysis are well consistent with the result from the SdH os cillation. From fast Fourier transform analysis for d2ρ/dB2-1/B，it is observed that there is a frequency of f1-f2 insensitive to the temperature, besides the frequencies f1, f2 for the two subbands and the frequency doubling 2f1, both depen dent on the temperature. This is because that the electrons occupying the two di fferent subbands almost have the same effective mass in the quantum well and the magneto-intersubband scattering between the two subbands is strong.
Exchange bias with perpendicular anisotropy in (Pt/Co)n/FeMn multilayers
Authors: Zhai Zhong-Hai  , Teng Jiao  , Li Bao-He  , Wang Li-Jin  , Yu Guang-Hua  , Zhu Feng-Wu  ,   (1)北京科技大学物理与化学系，北京  100083; (2)北京科技大学物理与化学系，北京  100083;北京工商大学数理部，北京  100037; (3)北京科技大学物理与化学系，北京  100083;沈阳建筑大学理学院,沈阳  110168
Published: December 2020

In this paper, we report the observation of exchange bias in (Pt/Co)n /FeMn multilayer with perpendicular magnetic anisotropy. The samples were deposi ted on glass substrates by magnetron sputtering and capped with 2nm thick Pt lay er. Our results show that the relation between perpendicular exchange bias Hex of (Pt/Co)n/FeMn multilayers and the thickness of antiferro magnetic layer is similar to that in the case of in-plane exchange bias. He x is inversely proportional to the number of bilayer repeats. In the case of (Pt/Co)3/FeMn multilayers, perpendicular exchange bias Hex reachs 22.3kA/m. With insertion of 0.4nm Pt layer between Co layer and FeMn layer, Hex can reach 39.8kA/m.
Single attosecond pulse generation by tightly focused laser beam-electron interaction
Authors: Cao Wei  , Lan Peng-Fei  , Lu Pei-Xiang  ,   激光技术国家重点实验室，武汉光电国家实验室，华中科技大学，武汉  430070
Published: December 2020

The nonlinear Thomson scattering by an electron in a focused circularly polarized laser beam is investigated and a novel scheme for single attosecond pulse generation is proposed.Through computer simulation we find that by using a tightly focused laser beam,the ratio of the highest peak pulse and the second highest peak pulse of the radiation which is defined as the signal-to-noise ratio can be efficiently increased, such that a single attosencond pulse rather than a train of attosecond pulses is obtained. The pulse duration of the radiation decreases and the signal-to-noise ratio increases with increasing laser intensity.Simultaneously,the signal-to-noise ratio can be also improved as the beam-waist decreases.We find that a single attosencond pulse can be generated by using a few-cycle ultrashort laser pulse as well.
State-vector function for a photon
Authors: Yao Zhi-Xin  , Pan Bai-Liang  , Chen Gang  , Zhong Jian-Wei  ,   浙江大学物理系，杭州  310027
Published: December 2020

On the basis of the generalized Schr?dinger equation， a novel state-vector function that obeys photon motion equation under three quantum conditions has been constructed for a photon in one dimension, which can describe completely the properties of a photon as a relativistic free particle, including its energy and momentum and spin angular momentum. The state-vector function not only defines microscopic parameters such as the probability amplitude and the phase for a photon, but also relates them with the macroscopic polarization of a light beam. As an example, it successfully explains the puzzling polarization problem of a light beam.
Mechanism of femtosecond laser-induced damage in magnesium fluoride
Authors: Li Cheng-Bin  , Jia Tian-Qing  , Sun Hai-Yi  , Li Xiao-Xi  , Xu Shi-Zhen  , Feng Dong-Hai  , Wang Xiao-Feng  , Ge Xiao-Chun  , Xu Zhi-Zhan  ,   中国科学院上海光学精密机械研究所强场激光物理国家重点实验室，上海  201800
Published: December 2020

Single-shot damage morphology of magnesium fluoride induced by femtosecond laser pulse was studied with scanning electron microscope (SEM). The laser pulses used were 800 nm central wavelength. By the linear relationship between the area of damage spot and the logarithm of the laser energy, we measured the dependence of damage threshold on the pulse duration ranging from 55 femtosecond (fs) to 750 fs. We have calculated the two-photon absorption in the conduction band and improved the multiple-equation model (Phys. Rev. Lett. 92 187401, 2004). The experimental results are well explained by our model.
Teleportation of a two-mode Gaussian state through double two-mode-squeezed-state quantum channels
Authors: Zhang Qian  , Li Fu-Li  , Li Hong-Rong  ,   (1)西安交通大学应用物理系，西安  710049; (2)西安交通大学应用物理系，西安  710049；西安邮电学院，西安  710061
Published: December 2020

Teleportation of a general two-mode Gaussian state through double two-mode squeezed state quantum channels is studied. It is found that the quantum channels must be enough entangled for the output state to be inseparable. The required minimum entanglement for the quantum channels to maintain entanglement in the output state depends on the entanglement of the input state when the input state is pure. The minimum entanglement depends not only the on entanglement but also on the global purity of the input state when the input state is mixed.
Simulated calculation and analysis of the forbidden band for fabricating two- and three-dimensional photonic crystal structures using holographic lithography
Authors: Liu Huan  , Yao Jian-Quan  , Li En-Bang  ,   天津大学精仪学院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

Compared with the semiconductor and micromachining fabrication technology, the holographic lithography method offers a number of advantages, including its ability to create large volume of periodic structures through one irradiation process, the uniformity of period, and more degrees of freedom to control the structures. In this study, a multi-beam interference model is presented for predicting two-and three-dimensional photonic crystal structures through designing the beam intensities, polarization directions and phase delays. Based on plane wave expansion method, complete forbidden bands of three-dimensional photonic crystals with fcc structure are also studied. The calculated results provide a useful guide for choosing proper optical parameters to fabricate two- and three-dimensional photonic crystal structures.
Dispersion equation of a helical slow wave structure filled with magnetized plasma
Authors: Xie Hong-Quan  , Liu Pu-Kun  ,   (1)西南科技大学理学院，绵阳  621010; (2)中国科学院电子学研究所，北京  100080
Published: December 2020

Analytical theory of electromagnetic field in a helical slow wave structure filled with plasma immersed in a finite axial magnetic field is presented in this paper. By means of helix sheath model and the boundary conditions, the dispersion equation of a magnetized plasma loaded helical slow wave structure is derived. Three particular cases (without plasma, without axial magnetic field and in infinite axial magnetic field) are discussed and the corresponding dispersion equations are deduced. It is found that the simplified results are in accord and with published references.
Theoretical analysis of polarization tracking based on half-wave plate
Authors: Ma Jing  , Zhang Guang-Yu  , Rong Yi-Wen  , Tan Li-Ying  ,   (1)哈尔滨工业大学可调谐激光技术国家级重点实验室，哈尔滨  150001; (2)哈尔滨工业大学可调谐激光技术国家级重点实验室，哈尔滨  150001;哈尔滨理工大学应用科学学院，哈尔滨  150080
Published: December 2020

The polarization tracking principle is analyzed by using a half-wave plate in satellite quantum key distribution and the polarization “zero” direction can be corrected by rotation of the half-wave plate. The transforms of six photon polarization states in three conjugative bases are given and the quantum key coding principle based on the polarization tracking is analyzed for the BB84 protocol and B92 protocol.
Monte Carlo simulation of the hole transport properties for wurtzite GaN
Authors: Guo Bao-Zeng  , Gong Na  , Shi Jian-Ying  , Wang Zhi-Yu  ,   河北大学电子信息工程学院,保定  071002
Published: December 2020

The simulation of the hole transport properties of wurtzite phase GaN are performed by the full band ensemble Monte Carlo approach. The band structure data of GaN used in the simulation are obtained by the empirical pseudopotential method. The scattering mechanisms included in the simulation are acoustic phonon scattering, optical phonon scattering, polar optical phonon scattering, piezoelectronic scattering, ionized impurity scattering, as well as the intervalley scattering. The dependence of the hole average drift velocity and average energy in three main symmetry directions for wurtzite GaN on the electric field are obtained. At room temperature, the velocity-field relation shows the non-saturated characteristics. The maximum drift velocity is about 6×106 cm s-1, and the maximum average energy is 0.12 eV in the range of the field of this work. These values are much smaller than the corresponding parameters of the electrons in GaN. Furthermore, the dependence of the diffusion mobility on the impurity density is reported.
Study on self-healing effect in ultra deep submicron PMOSFET’s
Authors: Li Jing  , Liu Hong-Xia  , Hao Yue  ,   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 NBTI effect is studied in this paper with emphasis on its self-healing phenomenon. The recovery of threshold voltage shift with stress times and recovery time are studied. It is found that the recovery is mainly related to the re-passivation by hydrogen of interface states that occurred after the stress is stopped.
Effect of hydrogen dilution on structure and optical properties of polycrystalline silicon films
Authors: Huang Rui  , Lin Xuan-Ying  , Yu Yun-Peng  , Lin Kui-Xun  , Zhu Zu-Song  , Wei Jun-Hong  ,   (1)汕头大学物理系，汕头  515063; (2)汕头大学物理系，汕头  515063；南京大学物理系，固体微结构物理国家重点实验室，南京  210093
Published: December 2020

Polycrystalline silicon films were prepared from SiCl4 diluted with hydrogen by plasma-enhanced chemical vapor deposition at a low temperature of 250℃. The effect of hydrogen dilution on their structure and optical properties were investigated. It was found that the effect of hydrogen on the growth behavior of the films deposited using SiCl4+H2 are completely different from that of using SiH4/H2. The crystalline fraction increases with decreasing the hydrogen dilution ratio R and reaches a maximum value of 85% at a low hydrogen dilution. However, further decreasing hydrogen dilution ratio leads the crystallinity to deteriorate and a phase transition between microcrystalline silicon and amorphous silicon is observed. The optical band gap gradually decreases from ～1.5eV to ～1.2eV and then increases up to 1.8eV with the decrease of the hydrogen dilution ratio. The deposition rate initially increases and then decreases with decreasing hydrogen dilution ratio, and no film is formed by using pure SiCl4. According to these results, we conclude that under the condition of optimum hydrogen dilution ratio, the enhanced crystalline fraction and the increase in grain size are attributed to the Cl radicals which play important roles in the low-temperature growth of crystalline silicon films.
The preparation of FePt/BN particle films with perpendicular texture by magnetron sputtering
Authors: Li Bao-He  , Feng Chun  , Yang Tao  , Zhai Zhong-Hai  , Teng Jiao  , Yu Guang-Hua  , Zhu Feng-Wu  ,   (1)北京科技大学材料物理系，北京  100083; (2)北京科技大学材料物理系，北京  100083；北京工商大学数理部，北京  100037; (3)北京科技大学材料物理系，北京  100083；沈阳建筑大学理学院,沈阳  110168
Published: December 2020

［FePt/BN］n multilayers were prepared on MgO (100) single crystal substrates at 250℃ with magnetron sputtering. The perpendicular texture of L10-FePt/BN particle films was formed after vacuum annealing. The results of X-ray diffraction and magnetic tests show that the ［FePt(2nm)/BN(0.5nm)］10 and ［FePt(1nm)/BN(0.25nm)］20 multilayers have excellent (001) texture when the films were sputtered on substrates at 250℃ after annealed at 700℃ for 1h. The mean size of L10-FePt particles is roughly 15—20nm and its perpendicular coercive force reaches 522 kA/m. Moreover, the Mr/Ms and switching filed distribution S* reach 0.99 and 0.94, respectively. This particle film is a candidate for future perpendicular magnetic recording media with ultrahigh density.
Formulation of the acoustically-induced electromagnetic field in a porous formation in terms of Hertz vectors and simulation of the borehole electromagnetic field excited by an acoustic multipole source
Authors: Guan Wei  , Hu Heng-Shan  , Chu Zhao-Tan  ,   (1)哈尔滨工业大学航天科学与力学系，哈尔滨  150001; (2)吉林大学物理学院，长春  130023
Published: December 2020

The electromagnetic field induced by acoustic waves in a porous formation is investigated. By supposing the acoustic field is not influenced by its induced electromagnetic field, the governing equations for the coupled acoustic and electromagnetic fields are reduced to a set of Maxwell equations with a propagation current source. The Maxwell equations are then transformed into inhomogeneous vector Helmholtz equations by introducing Hertz vectors. Finally the electromagnetic field is formulated in terms of the solutions to the Helmholtz equations. This method is used to evaluate the electromagnetic field during seismoelectric logging in a porous formation. The full waveforms of the acoustic field and the electromagnetic field in the borehole are calculated when the borehole acoustic sources are respectively a monopole, a dipole and a quadrupole.
Spectroscopic characteristics of transparent polycrystalline MgO and TiO2 codoped Al2O3 ceramics
Authors: Yang Qiu-Hong  , Zeng Zhi-Jiang  , Xu Jun  , Su Liang-Bi  ,   (1)上海大学材料科学与工程学院,上海  200072; (2)中国科学院上海光学精密机械研究所,上海  201800
Published: December 2020

Transparent polycrystalline MgO and TiO2 codoped Al2O3 ceramics were fabricated by conventional solid-state pressureless processing. The absorption, emission and excitation spectra of (Mg，Ti):Al2O3 ceramics were measured. Owing to charge compensation of Mg2+, only UV absorption around 250nm was observed due to O2-→Ti4+ charge transfer transitions (CT) when Ti content was low. As a result, the emission peaks of isolated Ti4+ ion located at 280—290nm and 410—420nm were observed. Besides absorption peak of Ti4+ ion, the characteristic absorption peak of Ti3+ ion centered at 490nm was observed in (Mg，Ti):Al2O3 ceramics when Ti content was high. The emission spectra of Ti3+ ion in polycrystalline Al2O3 ceramics coincide with that of Ti:Al2O3 single crystal.
Fiber-optic grating sensing based on thin-walled ring section beam
Authors: Xue Li-Fang  , Zhao Qi-Da  , Liu Jian-Guo  , Guo Tuan  , Huang Gui-Ling  , Liu Li-Hui  ,   南开大学现代光学研究所，天津  300071
Published: December 2020

Fiber-optic grating sensing based on Loop thin-walled ring section beam is proposed and demonstrated. The temperature and stress can be measured simultaneously using only one fiber grating. The strain of the thin-walled ring section beam is investigated theoretically and experimentally. The result shows the local strain varies as the cosine function of twice the positional angle.
Influence of the barriers on the ultrasonic nonlinear field distribution
Authors: Li Jun-Lun  , Liu Xiao-Zhou  , Zhang Dong  , Gong Xiu-Fen  ,   近代声学国家重点实验室，南京大学声学研究所，南京  210093
Published: December 2020

Based on Khokhlov-Zabolotkaya-Kuznetsov (KZK) equation in frequency-domain, an approach to study the three-dimensional asymmetric nonlinear ultrasonic field is developed in this paper. The ultrasonic nonlinear field distribution behind the simulated rib-like barriers is investigated by numerical simulation and compared with the measured results. In addition, the influence of the barriers on the spatial-and-time-averaged intensity is discussed, which is helpful for future study on the HIFU treatment behind the ribs.
Quick identification of EAST plasma discharge shape
Authors: Huang Qin-Chao  , Luo Jia-Rong  , Wang Hua-Zhong  , Li Chong  ,   (1)中国科学院等离子体物理研究所，合肥  230031; (2)中国科学院等离子体物理研究所，合肥  230031;解放军炮兵学院信息工程教研室，合肥  230031
Published: December 2020

To meet the requirement of plasma shape control running mode on experimental advanced superconducting tokamak(EAST), this paper studies the quick identification algorithm of plasma discharge shape and gives the results of reconstruction simulation. Moreover, the code is checked by the equilibrium reconstruction code EFIT provided by GA in U.S.A. Results show that we can identify the shape quickly by using external magnetic measurements and appropriate current profile in conjunction with real time equilibrium reconstruction algorithm.
The E1 and E2 vibrational modes at Γ point for chiral single wall carbon nanotubes
Authors: Peng Yong-Jin  , Zhang Hui-Peng  , Jin Qing-Hua  , Wang Yu-Fang  , Li Bao-Hui  , Ding Da-Tong  ,   南开大学物理系，天津  300071
Published: December 2020

The 12 non-degenerate phonon vibrational modes at the center of Brillouin zone for a series of single-wall carbon nanotubes have been analysed in a previous paper.［1］ The E1 and E2 of degenerate phonon vibrational modes are further discussed in this paper and the relations between frequency-chirality and frequency-tube diameter for E1 and E2 vibrational modes are also demonstrated.
Nonlinear dynamic behaviors of complex chaotic systems
Authors: Yu Jin-Jiang  , Cao He-Fei  , Xu Hai-Bo  , Xu Quan  ,   (1)北京应用物理与计算数学研究所，北京  100088; (2)大庆高等师范专科学校物理系，大庆市  163712; (3)石家庄学院物理研究所，石家庄  050035; (4)石家庄学院物理研究所，石家庄  050035;北京应用物理与计算数学研究所，北京  100088
Published: December 2020

In this paper, the nonlinear dynamical behaviors and bifurcation series of complex systems are studied. Numerical simulation and theoretical inference show that there are chaotic attractors in complex chaotic system which are sensitive to the initial states and are short of a boundary line.
Electron spin relaxation and momentum relaxation in semiconductor quantum wells
Authors: Wu Yu  , Jiao Zhong-Xing  , Lei Liang  , Wen Jin-Hui  , Lai Tian-Shu  , Lin Wei-Zhu  ,   中山大学光电材料与技术国家重点实验室，物理系，广州  510275
Published: December 2020

The dependence of electron spin relaxation on the momentum relaxation and carrier density are investigated based on the spin-orbit coupling and D'yakonov-Perel relaxation mechanism. Experimental results obtained by using femtosecond pump-probe technique in AlGaAs/GaAs multiple quantum wells at room temperature show that the spin relaxation time increases from 58 to 82ps with the carrier density increases from 1×1017 to 1×1018cm-3, consistent with the theoretical prediction. This results reveals that with the increase of the carrier density, the spin-orbit interaction reduces due to more frequent momentum scattering, sothat the spin relaxation time prolongs.
Fluorescence measurement and acoustic diagnostics of plasma channels in air
Authors: Hao Zuo-Qiang  , Zhang Jie  , Yu Jin  , Zhang Zhe  , Zhong Jia-Yong  , Zang Chong-Zhi  , Jin Zhan  , Wang Zhao-Hua  , Wei Zhi-Yi  ,   (1)Laboratoire de Spectrométrie Ionique et Moléculaire，UMR CNRS 5579，Université Claude Bernard-Lyon 1,43,Bd. du 11 Novembre 1918，F-69622 Villeurbanne Cedex，France; (2)北京大学物理学院，北京  100871; (3)中国科学院物理研究所光物理重点实验室，北京  100080; (4)中国科学院物理研究所光物理重点实验室，北京  100080;中国科学院国家天文台，北京  100012
Published: December 2020

A plasma channel up to 80 Rayleigh lengths is formed when intense femtosecond laser pulses propagate in air. Two methods, fluorescence measurement and acoustic diagnostics, are used to probe the plasma channel simultaneously. Both methods reveal the evolution of the channel in detail. Compared with the fluorescence measurement, the acoustic method is a convenient approach having higher sensitivity and higher spatial resolution in detecting long plasma channels.
Extraction of channel carrier concentration using C-V method for SiC buried-channel MOSFET
Authors: Gao Jin-Xia  , Zhang Yi-Men  , Tang Xiao-Yan  , Zhang Yu-Ming  ,   宽禁带半导体材料与器件教育部重点实验室，西安电子科技大学微电子学院, 西安  710071
Published: December 2020

A theoretical and experimental study on extracting channel carrier concentration for 4H-SiC buried channel MOSFET has been carried out. The distortion of C-V curve caused by the existence of p-n junction in buried channel MOS structure would affect the extracting result, and the interface states on SiO2/SiC interface make extracting result deviate from true channel carrier concentration. In this paper, firstly, a theoretical analysis about the effects of channel depth and interface state on extracting result is made. Then the C-V curves for buried-channel MOS structure with two different channel depth are presented from which the channel carrier concentration is extracted. In the measurement of C-V curves, three different sweep velocities are used to analyze the effect of interface states. The theoretical results agree with experimental results.
Spectroscopic behavior of Cr4+ in octahedral sites
Authors: Zhang Dan  , Su Liang-Bi  , Xu Jun  , Yang Qiu-Hong  , Zhang Lian-Han  , Li Hong-Jun  ,   (1)上海大学材料科学与工程学院，上海  200072; (2)中国科学院上海光学精密机械研究所，上海  201800
Published: December 2020

Cr-doped and Mg,Cr-codoped Al2O3 crystals were grown by Czochralski method. The latter has a broad absorption peak in 900—1600nm region. We investigated the change of the absorption band with annealing under different atmospheres or temperatures. Through establishing a structure defect model, we successfully interpreted all the experiment results and confirmed that the extremely broad infrared absorption band belonged to Cr4+, which should occupy the octahedral sites in Al2O3.
Stabilization of the multi-pin to multi-sphere plane negative corona discharge
Authors: Qi Bing  , Ren Chun-Sheng  , Ma Teng-Cai  , Wang You-Nian  , Wang De-Zhen  ,   大连理工大学物理系，三束材料改性国家重点实验室，大连  116023
Published: December 2020

In a multi-pin to multi-sphere plane DC negative corona discharge configuration at atmospheric pressure, stable and diffuse glow discharge has been obtained. The effect of the air flow velocity, the gap distance and the electrode structure on the discharge mode transition and the stabilization of the glow discharge is investigated by means of electric measurements and emission recording. The stabilization mechanism of the glow discharge is discussed. It is found that there is a transition phase characterized by Trichel pulse with DC component between corona and glow discharge.
Investigation of a new type nano carbon film prepared by high energy plasma assisted CVD
Authors: Yang Wu-Bao  , Fan Song-Hua  , Ge Min  , Zhang Gu-Ling  , Shen Zeng-Min  , Yang Si-Ze  ,   (1)北京化工大学碳纤维研究所，北京  100029; (2)中国科学院物理研究所，北京  100080; (3)中国石油大学机电学院，北京  102249
Published: December 2020

Using self-fabricated equipment, new type carbon films with unfamiliar properties, high hardness and good electric conductivity were deposited on 1Cr18Ni9Ti substrate under deposition parameters of ion energy 2keV, pressure 2Pa, and methane ratio in hydrogen 10%. Process review shows that the substrate material is the key factor for the carbon films deposition, and the parameters of ion energy, pressure and methane ratio are impotent also. The grain size is less than 100nm and the film is smooth, dense and uniform as tested by AFM. Raman spectra show that there is only one broaden peak around 1580cm－1. The sheet resistance of the film is 1.6×104Ω/cm2 as measured with the ohmmeter. The micro-hardness of the film is 21.38GPa and the bulk elasticity is 420.65GPa as tested by nano-indenter. It is concluded that there may be carbon chain structure in this film.
Measurements of electric resistivity of plasma channels in air
Authors: Zhang Zhe  , Zhang Jie  , Li Yu-Tong  , Hao Zuo-Qiang  , Zheng Zhi-Yuan  , Yuan Xiao-Hui  , Wang Zhao-Hua  ,   (1)中国科学院物理研究所光物理开放实验室，北京  100080; (2)中国科学院物理研究所光物理开放实验室，北京  100080;中国科学院西安光学精密机械研究所瞬态光学技术国家重点实验室，西安  710068
Published: December 2020

A long plasma channel can be formed when ultra-intense femtosecond laser pulse propagate, in air. We measured the value of the resistivity of the plasma channel and the contact resistance between the plasma channel and the electrodes. We also investigated the main factors affecting the resistivity of the plasma channel.
Charge order phase and reentrant spin-glass behavior in half doped Sm0.5Ca0.5MnO3 manganite
Authors: Wang Shi-Peng  , Zhang Jin-Cang  , Cao Gui-Xin  , Yu Jian  , Jing Chao  , Cao Shi-Xun  ,   上海大学物理系，上海  200436
Published: December 2020

The structure, transport and magnetic properties of half doped Sm0.5Ca0.5MnO3 manganite has been systamatically studied. The results show that Sm0.5Ca0.5MnO3 compound has the O′orthorhombic structure and shows typical Jahn-Teller distortion. Throughout the temperature range used, the electric transport shows semiconducting behavior and there are no I-M transition and CMR effect. Meanwhile, it is found that the charge-order and antiferromagnetic transition temperatures of the system are around 270K and 200K, respectively, whereas at lower temperature there appears a typical spin-glass state around 41K with reentrant behavior. The negative magnetization is also observed in this compound. All these phenomena indicate that for the ground state of Sm0.5Ca0.5MnO3, there exists the competition mechanism of several complex magnetic interactions. Present study may provide abundant experimental information for understandig the mechanism of the strongly electron correlated system.
Structure and formation of misfit dislocations in an epitaxial fcc film
Authors: Zhou Nai-Gen  , Zhou Lang  , Du Dan-Xu  ,   (1)Princeton Institute for Science and Technology of Materials,Princeton University,Princeton,NJ 08542; (2)南昌大学 材料科学与工程学院，南昌  330047
Published: December 2020

Three-dimensional molecular dynamics simulation of epitaxial growth of fcc aluminum film with a negative misfit of 0.05, under atomic deposition, has been carried out. An embedded atom method (EAM) potential is employed for computing atomic interaction in aluminum. Formation of misfit dislocation appears in the simulated growth process. Atomistic analysis of the film shows that, in the beginning the misfit dislocation consists of two Shockley partial dislocations with a stacking fault zone between them. The Burgers vectors of the two partial dislocations are of 〈211〉/6 type, and the width of the stacking fault is ～1.8 nm, which agrees well with theoretical calculation. During further deposition growth, the dislocation pair can slide, but their distance remains stable. Further analysis shows that the dislocation pair forms in a local surface disordering-ordering process, like the local melting-crystallization. Atomic scale squeezed-out tetrahedrons are found to form near the surface and soon slide back in the anor of statistical fluctuation. Under some circumstances, however, a squeezed-out tetrahedron causes disorder of its neighboring atoms, and developes into the observed local disorder zone, which later becomes the nucleation site for the formation of the Shockley dislocation pair.
Energy calculation of the stacking fault in fcc metals by embedded-atom method
Authors: Zhang Jian-Min  , Wu Xi-Jun  , Huang Yu-Hong  , 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

The stacking fault energies of fcc metals have been calculated by the embedded-atom method for 10 fcc metals, Cu, Ag, Au, Ni, Al, Rh, Ir, Pd, Pt and Pb. The calculated values are in good agreement with experimental results, that of Rh and Ir excepted.
SiGe HBT large signal equivalent circuit model
Authors: Hu Hui-Yong  , Zhang He-Ming  , Lü Yi  , Dai Xian-Ying  , Hou Hui  , Ou Jian-Feng  , Wang Wei  , Wang Xi-Yuan  ,   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

A large signal equivalent circuit model for SiGe HBT is established based on the physical model of the transistor. The quasi saturation effect and the self-heating effect are taken into account in this equivalent circuit model. The model is composed of the intrinsic and the extrinsic parts, and has the features of clear physical meaning and simple topology. The model is embedded in the DEVEQ(Device Equations Developer) of PSPICE and simulated and analyzed by the PSPICE. The results conform to the theoretically analyzed conclusion and are in accordance with the published results in the literature.
The effect of solution treatment on the spatial behavior of the Portevin-Le Chatelier effect in Al-Cu alloys
Authors: Jiang Hui-Feng  , Zhang Qing-Chuan  , Xu Yi-Hao  , Wu Xiao-Ping  ,   中国科学技术大学，中科院材料力学行为和设计重点实验室，合肥  230027
Published: December 2020

The effect of solution treatment on the spatial behavior of the Portevin-Le Chatelier effect in Al-Cu alloys is investigated under constant applied driving velocity. During the initial stage of plastic deformation, the PLC deformation band nucleates in the neighborhood of the middle of the transverse direction of specimen. And multiple bands will exist simultaneously in the specimen when deformation develops, whose width is narrower and incline at a larger angle than those in annealing treated material. At high applied velocity, the PLC deformation band propagates continuously first, and then nucleates randomly in the specimen.
Surface tension of a highly supercooled Ni-15%Sn alloy melt
Authors: Zhang La-Bao  , Dai Fu-Ping  , Xiong Yu-Ying  , Wei Bing-Bo  ,   (1)华南师范大学物理与电信工程学院，广州  510631; (2)西北工业大学应用物理系，西安  710072; (3)西北工业大学应用物理系，西安  710072;华南师范大学物理与电信工程学院，广州  510631
Published: December 2020

The surface tension of supercooled liquid Ni-15%Sn alloy was measured by the electromagnetic oscillating drop method over a wide temperature range from 1368 to 1915K. The maximum supercooling of 265K(0.16TL) was achieved. Over the temperature range investigated, the measured surface tension shows a linear property expressed by σNi-15%Sn=1316.7-1.01(T-TL)mN/m. On the basis of experimental data, the viscosity and the diffusion coefficient of Ni-15%Sn melt were derived, and we also analyzed the activation energy for viscous flow and diffusion.
Regularity of multiplication of chaotic maps
Authors: Yu Jin-Jiang  , Xu Hai-Bo  ,   (1)北京应用物理与计算数学研究所，北京  100088; (2)石家庄学院物理系，石家庄  050035;石家庄学院物理研究所，石家庄  050035;北京应用物理与计算数学研究所，北京  100088
Published: December 2020

The multiplication of chaotic maps is analyzed theoretically in this paper. The result of our computer simulation shows that the new chaotic map, combined by several chaotic maps, still has chaos attractors and is sensitive to the initial states.The concept of multiplication of chaotic maps is important in theory and applications.
Simulation of 3-dimensional thin film growth on heterogeneous substrate
Authors: Lu Hang-Jun  , Wu Feng-Min  ,   浙江师范大学凝聚态物理研究所，金华  321004
Published: December 2020

A kinetic Monte Carlo model describing the three-dimensional thin film growth on heterogeneous substrates is presented, in which the diffusion of adatoms on substrates, along the island edges and between various layers, as well as the heterogeneity of adsorptive energy, are taken into account. Three growth modes, namely the Layer-by-layer mode, Stranski-Krastanovs mode and 3D mode, and the morphology of multiple layer growth of thin films are simulated. The relationship between thin film growth modes and growth conditions is established by taking into account the distribution of deposited atoms on various layers and the surface roughness of thin films.
Thermodynamic explanation of solid-state reactions in synthesis process of CoSb3 via mechanical alloying
Authors: Liu Wei-Shu  , Zhang Bo-Ping  , Li Jing-Feng  , Liu Jing  ,   (1)北京科技大学材料科学与工程学院无机非金属材料系，北京  100083; (2)清华大学材料科学与工程系新型陶瓷与精细工艺国家实验室，北京  100084
Published: December 2020

CoSb3 powders were synthesized by mechanical alloying (MA) with Co and Sb powders as starting materials. The influence of milling speed and duration on the solid reaction were systematically studied. The XRD results indicated that the CoSb3 phase increased with prolonged MA-time, but extensive MA resulted in the appearance of CoSb2 and the decomposition of CoSb3 to CoSb2 and amorphous Sb at a constant MA-speed. Increasing the MA-speed can shorten the incubation time of the reaction, but doesn't influence the MA solid reactions themselves. For MA processes that give a specific state of alloying, the MA-speed and the MA-time should satisfy the relationship: ω3.8t=C(constant), which expresses the relationship of equivalency between MA-speed and MA-time, indicating that the supplied energy is being accumulated during MA. The MA mechanism concerning the formation of CoSb3 has been discussed on the basis of MA from a viewpoint of non-equilbrium thermodynamics.
Grain fragmentation and property modification of nanocrystalline ZnO under high pressure
Authors: Shao Guang-Jie  , Qin Xiu-Juan  , Liu Ri-Ping  , Wang Wen-Kui  , Yao Yu-Shu  ,   (1)`中国科学院物理研究所，北京  100080; (2)燕山大学亚稳材料科学与技术重点实验室，秦皇岛  066004; (3)燕山大学亚稳材料科学与技术重点实验室，秦皇岛  066004;中国科学院物理研究所，北京  100080
Published: December 2020

Grain fragmentation and property modification of nanocrystalline ZnO under high pressure were studied on CS-1B 6×8000 kN cubic high pressure apparatus. Grain size and microstructure of the samples have been characterized by X-ray diffraction and field emission scanning electron microscopy. The results show that the significant grain fragmentation phenomenon occurs inside the crystallites. Experimental results on hardness and the current-voltage characteristics indicate that micro-hardness of the samples after high pressure is 2.3 times that of the samples sintered at atmospheric pressure and the nonlinear current-voltage characteristics is obviously better than that of the latter.
Approximate analytic solution of land-air couplind dynamical system
Authors: Mo Jia-Qi  , Wang Hui  , Lin Wan-Tao  ,   (1)安徽师范大学,芜湖  241000;上海高等院校计算科学院E研究院，上海交通大学研究所，上海  200240; (2)中国科学院大气物理研究所,北京  100029; (3)中国气象科学研究院，北京  100081
Published: December 2020

Atmospheric physics deals with very complicated natural phenomena. Basic models have to be implemented for the sea-air and land-air oscillators and then solve them using the approximate method. In this paper, a class of nonlinear coupling system for land-air oscillator model is studied. Using the homotopic mapping method, it is translated into solving linear problems, and the approximate expressions for the original nonlinear problem are obtained.
Density profile of a superfluid Fermi gas with a phase slip
Authors: Wu Hong-Yu  , Yin Lan  ,   北京大学物理学院，北京  100871
Published: December 2020

BEC(Bose Einstein Condensation)-BCS(Bardeen Schrieffer Cooper) crossover is currently one of the main research focuses in the area of cold atoms and BEC. In this paper, we study in detail the phenomenon of a phase slip in a superfluid Fermi gas near a Feshbach resonance, based on our previous work. The density profiles of a superfluid Fermi gas with a phase slip at various temperatures are computed by numerical method. Our results show that the phase-slip phenomenon can provide a direct experimental evidence of the superfluid phase.
Analysis of evolution and life-time of the plasma channel produced by ultra-stort ultra-high power laser pulse
Authors: Tang Rong-Rong  ,   湖州师范学院理学院,湖州  313000;上海高等院校计算科学E-研究院，上海交通大学研究所，上海  200240
Published: December 2020

Using the perturbed theory, the plasma channel produced by ultra-short ultra-high power laser pulses is considered. Under the actions of recombination, attachment and detachment, the perturbed asymptotic expressions of the density of each kind of charged particles in the course of evolution of the plasma channel are obtained. The influence of each action on the evolution and life_time of the channel is discussed.
Form invariance and non-Noether conserved quantity of generalized Raitzin’s canonical equations of non-conservative system
Authors: Qiao Yong-Fen  , Zhao Shu-Hong  ,   (1)东北农业大学工程学院，哈尔滨  150030; (2)浙江理工大学机械工程与自动化系，杭州  310018;东北农业大学工程学院，哈尔滨  150030
Published: December 2020

The form invariance and the non-Noether conserved quantity of generalized Raitzin's canonical equations of non-conservative system are studied. The definition and criterion of the form invariance in the system under infinitesimal transformations are proposed. The necessary and sufficient condition under which the form invariance is a Lie symmetry is given. The Hojman theorem is established. Finally, an example is given to illustrate the application of the result.
Non-Noether conserved quantities for systems with unilateral non-Chetaev nonholonomic constraints
Authors: Zhang Yi  ,   苏州科技学院土木工程系，苏州  215011
Published: December 2020

This paper studies the symmetries and non-Noether conserved quantities of mechanical systems with unilateral non-Chetaev nonholonomic constraints. The differential equations of motion of the systems are established, and the definitions and criterions of Lie symmetry and Mei symmetry are given. For the unilateral non-Chetaev nonholonomic constraint system, it is proved that under some conditions a new conserved quantity called Hojman conserved quantity can be directly deduced from Lie symmetry, and a new conserved quantity called Mei conserved quantity can be directly deduced from Mei symmetry. The relations between the symmetries and the new conserved quantities are researched. At the end of the paper, an example is given to illustrate the application of the results.
Extended mapping approach and new solutions of the (2+1)-dimensional breaking soliton equations
Authors: He Bao-Gang  , Xu Chang-Zhi  , Zhang Jie-Fang  ,   (1)浙江师范大学非线性物理研究所，金华  321004; (2)浙江师范大学非线性物理研究所，金华  321004;金华教育学院物理系，金华  321000
Published: December 2020

Extended mapping approach is introduced to solve the (2+1)-dimensional breaking soliton equations. On its basis, abundant propagating and non-propagating structures are found by selecting the arbitrary function appropriately. However, only periodic soliton wave structures are revealed in this paper.
Bound states of the Klein-Gordon equation and Dirac equation with the Manning-Rosen scalar and vector potentials
Authors: Zhang Min-Cang  , Wang Zhen-Bang  ,   陕西师范大学物理学与信息技术学院,西安  710062
Published: December 2020

The s-wave bound states of the Klein-Gordon equation and Dirac equation with equal Manning-Rosen scalar and vector potentials are obtained, and the solutions are expressed by the hypergeometric function.
Entanglement decoherence of two-particle entangled states in a noisy environment
Authors: Xiang Shao-Hua  , Song Ke-Hui  ,   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

Entanglement decoherence of two particles interacting with the same environment is investigated by means of concurrence and the input-output fidelity. It is found that the entangled states of two-particle system can be divided into two kinds, coherence-preserving states and fragile entangled states. The dynamics of entanglement decoherence for fragile entangled states is discussed by taking into account the ohmic dissipation under the low temperature approximation.
The quantum tunneling effect of Reissner-Nordstr?m de Sitter black hole
Authors: Li Hui-Ling  , Jiang Qing-Quan  , Yang Shu-Zheng  ,   西华师范大学理论物理研究所，南充  637002
Published: December 2020

Adopting Parikh's mode of quantum radiation as tunneling, the tunneling effect of Reissner_Nordstrm de Sitter black hole is studied. Under implementation of energy conservation, the result shows that the emission of the particle on the event horizon and the cosmic horizon is related with the change of Bekenstein_Hawking entropy and that the spectrum is not precisely thermal.
Controlling chaos in permanent magnet synchronous motor based on the differential geometry method
Authors: Wei Du-Qu  , Luo Xiao-Shu  , Fang Jin-Qing  , Wang Bing-Hong  ,   (1)广西师范大学物理与信息工程学院，桂林  541004; (2)中国科学技术大学近代物理系，合肥  230026; (3)中国原子能科学研究院，北京  102413
Published: December 2020

Recent investigation has shown that the permanent magnet synchronous motor(PMSM) may have chaotic behaviors for cortain values of parameters or under certain working conditions,which threatens the secure and stable operation of motor-driven.Hence,it is important to study methods of controlling or suppressing chaos in PMSM.Using the exact linearization theory of differential geometry,a law of controlling chaos in PMSM is deduced in this paper, and then,the process of controlling is simulated and analyzed.Theoretical analysis and simulation results show that the deduced control law is effective and its control property is better than that of other methods.Our results may help to maintain the system's secure operation.
A kind of Fredholm type weak singular kernel integral equation with triangle function as free term
Authors: Wang Li-Min  , Ren Chuan-Bo  , Xu Shi-Lang  , Zhao Xi-Qiang  ,   (1)大连理工大学土木工程系，大连  116024; (2)山东理工大学交通与车辆学院力学部，淄博  255049; (3)中国海洋大学数学系，青岛  266003
Published: December 2020

For a type of Fredholm integral equation with weak singularity integral kernel of logarithm function, the exact solutions is deduced through a calculus procedure when the free term is a triangle function. The singular character of solution is also analyzed when the variable is approaching the extreme points.