bluuebunny/crossref_metadata_2025 huggingface dataset:
Transport properties and magnetoresistance of nano-polycrystalline La0.7Sr0.3MnO3－δ
Authors: Xi Li  , Yang Xiao-Lin  , Li Cheng-Xian  , Ge Shi-Hui  ,   兰州大学磁学与磁性材料教育部重点实验室，兰州  730000
Published: December 2020

The resistivity and magnetoresistance of bulk polycrystalline La0.7Sr0.3MnO3-δ, fabricated to produce nanoscale grains sintered at different temperatures, have been investigated as functions of temperature. With decreasing temperature below room temperature the resistivity (ρ) exhibits a maximum near 250K, below which it shows “metallic" behaviour, i.e. ρ∝T2 in the temperature range from 50K to 170K. However, ρ subsequentlyexhibits a minimum near 50K, below which it is well fit by the predictions of the tunneling of conduction electrons through insulating interfacial layers, viz lnρ ∝T1/2, a result interpreted as conduction-electron tunneling between adjacent LSM granules. The minimum of ρ occuring in these samples may result from the competition of the tunneling effect and the intrinsic metallic transport mechanism of LSM. The temperature dependence of the associated tunneling magnetoresistance is also reported.
Influence of charging parameters on piezoelectricity for cellular PP film electrets
Authors: Zhang Peng-Feng  , Xia Zhong-Fu  , Qiu Xun-Lin  , Wang Fei-Peng  , Wu Xian-Yong  ,   同济大学波耳固体物理研究所，上海  200092
Published: December 2020

The influence of charging parameters (such as charging voltage, charging time and charging temperature, etc.) on piezoelectricity and its thermal stability of cellular polypropylene film electrets was studied by means of contact charging and constant voltage corona charging methods and the thermal stimulated discharge technique. The cause of the influence is discussed in connection with the structure and the theoretic model of the cellular piezoelectric film electrets, and its dynamic characteristic of space charge is also analyzed. The results show that the piezoelectricity and its thermal stability of these electrets may be improved by optimizing the charging parameters.It is hoped that this work will be helpful to widen the application of cellular PP and will offer theoretic and technical basis for its industrialization.
Mei symmetries of a type of dynamical equations
Authors: Ge Wei-Kuan  ,   湖州师范学院物理系,湖州  313000
Published: December 2020

The definition and the criterion of a Mei symmetry for a type of dynamical equations are presented. The Noether conserved quantity can be deduced when the Mei symmetry is a Noether symmetry .The Hojman conserved quantity can be obtained if the Mei symmetry is a Lie symmetry. In addition, a new conserved quantity can be found by the Mei symmetry.
Core center distribution of Nd∶YAG crystal grown by Temperature gradient technique
Authors: Jiang Ben-Xue  , Xu Jun  , Li Hong-Jun  , Wang Jing-Ya  , Zhao Guang-Jun  , Zhao Zhi-Wei  ,   (1)中国科学院上海光学精密机械研究所，上海  201800; (2)中国科学院上海光学精密机械研究所，上海  201800；中国科学院研究生院，北京  100049
Published: December 2020

Large size (φ75 mm) high quality Nd∶YAG crystals were grown by the temperature gradient technique(TGT). The carbon atoms were eliminated after O2 annealing. We have studied the core distribution and growth stripes by Zygo interferometer and orthogonal polarization microscope. The absorption spectra of Nd∶YAG crystal at room temperature have been measured. The distribution of Nd ions in Nd∶YAG crystal were studied by using absorption spectra. A comparison of temperature gradient technique and Czochralski (Cz) grown Nd∶YAG crystals was made.
Studies on electrical properties of delta-doping p-GaN films
Authors: Li Tong  , Wang Huai-Bing  , Liu Jian-Ping  , Niu Nan-Hui  , Zhang Nian-Guo  , Xing Yan-Hui  , Han Jun  , Liu Ying  , Gao Guo  , Shen Guang-Di  ,   北京工业大学北京市光电子技术实验室，北京  100022
Published: December 2020

Mg delta-doped GaN epilayers have been grown by metalorganic chemical vapor deposition, and their characteristics have been investigated. It is shown that not only the p-type conduction, but also the overall quality of p-GaN is improved by delta-doping. It is observed that the dislocation density is reduced due to the growth interruption. A pre-purge step has been employed during delta-doping process, but the carrier concentration was decreased by the pre-purge.
Calculation of exciton energies and binding energies in ZnO film
Authors: Xiong Wen  , Zhao Hua  ,   重庆大学数理学院物理系和凝聚态物理研究所,重庆  400044
Published: December 2020

In this paper, a coupled 6×6 Hamiltonian valence eigenfunction is considered using effective mass approximation. Using a trial wave function separable in z direction and x-y plane, variational calculations are presented for energies of ground state and first excited state of heavy hole exciton and binding energies in ZnO film, and for radius of exciton under a variety of thickness d of ZnO film. And the correction of energies due to quantum tunnel effect of electronic wave function with the thickness d<2.0 nm is discussed.
Phonon damping in two-dimensional Heisenberg ferromagnetic system at finite temperature
Authors: Cheng Tai-Min  ,   沈阳化工学院数理系，沈阳  110142
Published: December 2020

A magnon-phonon interaction model is developed on the basis of two-dimensional square Heisenberg ferromagnetic system. The transverse acoustic phonon damping and longitudinal acoustic phonon damping are studied through Matsubara Green function theory, and transverse acoustic phonon damping and longitudinal acoustic phonon damping curves are calculated on the main symmetric point and line in the first Brillouin zone. It’s found that in the first Brillouin zone, on line Δ, there is no damping for the transverse acoustic phonon, on line Z, there is no damping for longitudinal acoustic phonon. In the first Brillouin zone, the transverse acoustic phonon damping is one order larger than the longitudinal acoustic phonon damping. The influences of transverse acoustic phonon damping and longitudinal acoustic phonon damping for different parameters on them are also illustrated in this article. According to the relationship between phonon damping and phonon lifetime, and the relationship between phonon damping and phonon density of state, the lifetime and density of state for transverse acoustic phonon and longitudinal acoustic phonon is discussed.
Room-temperature photoluminescence of ZnO/MgO multiple quantum wells deposited by reactive magnetron sputtering
Authors: Xin Ping  , Sun Cheng-Wei  , Qin Fu-Wen  , Wen Sheng-Ping  , Zhang Qing-Yu  ,   (1)大连理工大学三束材料改性国家重点实验室，大连  116024; (2)大连理工大学三束材料改性国家重点实验室，大连  116024；半导体材料科学重点实验室中国科学院半导体研究所,北京  100083; (3)清华大学材料科学与工程系，北京  100084
Published: December 2020

Wurtzite ZnO/MgO superlattices were successfully grown on Si(001) substrates at 750℃ using radio-frequency reactive magnetron sputtering method. X-ray reflection and diffraction, electronic probe and photoluminescence analysis were used to characterize the multiple quantum wells (MQWs). The results showed the periodic layer thickness of the MQWs to be 1.85 to 22.3 nm. The blueshift induced by quantum confinement was observed. Least square fitting method was used to deduce the zero phonon energy of the exciton from the room-temperature photoluminescence. It was found that the MgO barrier layers has a much larger offset than ZnMgO. The fluctuation of periodic layer thickness of the MQWs was suggested to be a possible reason causing the photoluminescence spectrum broadening.
Top-emitting organic light-emitting devices with cavity effect
Authors: Cao Jin  , Liu Xiang  , Zhang Xiao-Bo  , Wei Fu-Xiang  , Zhu Wen-Qing  , Jiang Xue-Yin  , Zhang Zhi-Lin  , Xu Shao-Hong  ,   上海大学新型显示技术与应用集成教育部重点实验室，上海大学材料学院，上海  201800
Published: December 2020

Top-emitting organic light-emitting devies (TOLEDs) have been constructed with Ag/ITO reflective anode and LiF/Al/Ag semi-transparent cathode. The cavity effect have been researched by using Alq and TBADN:TBPe as emitting layers respectively. Different colors from the same emitting layer have been realized by changing the thickness of ITO. For Alq-based TEOLEDs, the full width at half maximum(FWHM) was narrowed to 20—40 nm from the 100 nm of bottom-emitting organic light-emitting devices (BEOLEDs). the EL peak was shifted from 500 nm to 584 nm by changing the thinckness of ITO. The maximun current efficiency of the TOLEDs is 1.77 cd/A, which approaches to the 1.8 cd/A of tranditional devices. For TBADN:TBPe-based devices, the FWHM was narrowed to 20 from BEOLEDs's 65 nm. the EL peak was shifted from 464nm to 532 nm by changing the thinckness of ITO, and navy blue with CIE coordinates x=0.141,y=0.049 have been obtained by TBADN:TBPe-based TEOLEDs with cavity effect.
Surface roughening and growth mode transition of polycrystalline thin films
Authors: Yang Ji-Jun  , Xu Ke-Wei  ,   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

Surface roughening of Cu and Ta polycrystalline thin films deposited by magnetron sputtering at different homologous temperature Ts/Tm (Ts and Tm are the substrate temperature and the material melting point, respectively) have been studied using atomic force microscopy. With increasing Ts/Tm, the surface roughness of the films increased and growth exponent first increased and then decreased. The observed temperature dependence of growth exponent indicates a transition of growth modes from random growth at lower Ts/Tm through surface diffusion-dominated growth at intermediate Ts/Tm to anomalous scaling growth at higher Ts/Tm. We also found that the surface roughening of the films reflects the anomalous scaling behavior when the value of Ts/Tm is lower than 0.41, which implies that the boundary diffusion mechanism plays an important role in the scaling behavior of surface roughening.
Element-specific in-plane magnetic anisotropy in Co0.9Fe0.1 films
Authors: Guo Yu-Xian  , Wang Jie  , Xu Peng-Shou  , Li Hong-Hong  , Cai Jian-Wang  ,   (1)中国科学技术大学国家同步辐射实验室，合肥  230029; (2)中国科学院物理研究所磁学国家重点实验室，北京  100080
Published: December 2020

Utilizing X-ray magnetic circular dichroism spectra we have investigated in-plane element-specific magnetic anisotropy in Co0.9Fe0.1 films. Apart from known field-induced easy axis during film growth, a soft axis perpendicular to it was observed, and the hard axis is 66°away from the easy axis. Thus in-plane bi-axisial anisotropy is realized. For different contents of Co and Fe, the variation trends of magnetic moment per hole in different magnetization directions are similar, and the values of magnetic moment of Fe is about 87% that of Co, which suggested that there exists strong ferromagnetic coupling between Fe and Co atoms.
Study of structure stability and decoration of carbon nanotube under applied electric field
Authors: Xia Ming-Xia  , Yan Ning  , Li Hong-Xing  , Ning Nai-Dong  , Lin Xi-Wei  , Xie Zhong  ,   (1)Intel Corporation M/S RA3-402,2501 NW 229th Av. Hillsboro,Oregon  97124,USA; (2)湖南大学微纳技术研究中心，长沙  410082; (3)湖南大学应用物理系，长沙  410082
Published: December 2020

Structure stability of multi-walled carbon nanotube under applied electric field has been investigated. The results show that anti-bonding between carbon atoms at the tip of nanotube resulting from the local field strength of ～30V/nm leads to structure instability. Using the electron microscope as the nanolaboratory, we have prepared amorphous carbon nanowires on the tip by incorporation of foreign hydrocarbon under the applied electric field, resulting in the nanotube/nanowire structure. Electric measurement indicates that the nanotube/nanowire structure has rectifying characteristics. Consequently, the applied electric field may have potential applications in structure decoration and device fabrication of carbon nanotubes.
Temperature effects of optical bistability of metal/dielectric granular composites
Authors: Chen Guo-Qing  , Wu Ya-Min  , Lu Xing-Zhong  ,   (1)常州工学院理学院，常州  213002; (2)江南大学理学院，无锡  214122
Published: December 2020

Based on effective medium approximation, self-consistent mean field approximation and the spectral representation method were adopted to investigate the temperature dependence of optical bistability of metal/dielectric granular composite. Numerical calculations were used to find out the temperature effects on optical bistability at different values of incidence frequency, volume fraction and shape factor. The results show that the emergence of optical bistability, optical bistability threshold and threshold width are all greatly dependent upon the temperature.
Combustion synthesis and photoluminescence of nanocrystalline Gd2O3:Eu3+
Authors: Peng Zhi-Wei  , Wang Ling-Ling  , Liu Huang-Qing  , Huang Wei-Qing  , Zou Bing-Suo  ,   湖南大学应用物理系，长沙  410082
Published: December 2020

Nanocrystalline Gd2O3:Eu3+ was prepared by modified combustion synthesis using citric acid as the fuel and metal nitrates as oxidants. By using X-ray diffraction (XRD)，high resolution transmission electron microscopy (HRTEM) and fluorescence spectrophotometry, the structural, morphological and luminescent properties of the nanocrystals were investigated. The results showed that Gd2O3:Eu3+ nanocrystal with pure cubic phase was produced after the samples prepared using different citric acid-to-metal nitrate (C/M) molar ratios were calcined at 800℃ for 1 hour. The grain size was approximately 30 nm and the size distribution was narrow. The Gd2O3:Eu3+ nanocrystals whit C/M ratio 1.0 had the best crystallinity and strongest photoluminescence. The main emission peak of Gd2O3:Eu3+ nanocrystal was 612 nm, being attributed to 5D0→7F2 transition. The charge transfer state had an obvious red shift in the excitation spectrum. The efficient energy transfer from Gd3+ to Eu3+ was also observed. In addition, the influences of C/M molar ratio on crystallinity and luminescent properties were studied and discussed.
The influence of base pair sequence on electronic structure of DNA molecules
Authors: Xu Hui  , Guo Ai-Min  , Ma Song-Shan  ,   中南大学物理科学与技术学院，长沙  410083
Published: December 2020

The DNA molecule is considered as one-dimensional disordered binary system. Its electronic structure is discussed in terms of base pairs′ relative percentage and distribution using the density of electronic states which are calculated by the negative eigenvalue theory. The result shows that the effect of the base pairs′ relative percentage and distribution on the electronic energy state structure is great. In other words, the sequence of the base pairs plays an important role in determining the electronic structure.
Characteristics of the synchrotron radiation from relativistic electrons in plasma
Authors: Liu Jiong  , Yuan Ye-Fei  , Deng Xiao-Long  ,   中国科学技术大学天体物理中心，合肥  230026
Published: December 2020

According to synchrotron radiation theory, we derive the absorption coefcient, emission coefficient, and the emission intensity from relativistic electrons in the plasma under the different kinds of magnetic fields. Furthermore, we study the maser effect of the synchrotron radiation. The effects of two kinds of magnetic fields are investigated, the first kind is a curved magnetic field, but its strength is homogenous. The other is a dipole magnetic field. We find some special characteristics in the dipole magnetic field. Because of the uncertainty of the energy distribution spectrum of electrons, we choose three typical energy distribution spectra, namely the power law spectrum, Gauss spectrum and thermal spectrum. By calculating the emission intensity, we find the maser effect of synchron-curvature radiation under several kinds of astronomical condition. It is clearly shown that the maser emission of the synchrotron radiation does exist in plasma environment. These results could give some explanations for the atmospheric radiation of planets and might be helpful to solve the problems of the high brightness temperature of some radio sources.
Further discussion on the entropy of Dirac field in spherically symmetric non-static black hole
Authors: Zheng Yuan-Qiang  ,   阆中治平中学物理研究组,阆中 637400
Published: December 2020

A new general tortoise coordinate transformation is used with the thin film brick-wall model.We further discuss the Hawking temperature and the entropy of Dirac field in spherically symmetric non-static black hole.The cut-off parameter does not vary for different time-space structure,and it is reduced to that of the stationary cases.
Eigenaction of metric operator on Gaussian weave state and spin-geometry
Authors: Shao Dan  , Shao Liang  , Shao Chang-Gui  , H.Noda  ,   (1)Department of Mathematical Sciences,Ibaraki University,Mitio 310-8512,Japan; (2)湖北教育学院理论物理所，武汉 430205; (3)江汉大学光电信息研究所，武汉 430056; (4)武汉科技大学理学院应用物理系，武汉 430081
Published: December 2020

In the recouping theorem and the graph calculation for loop quantum gravity, it is proved that the action of metric matrix operator on Gaussian weave state is an eigenaction, and the representation matrix elements of the metric operator and their expectation values are calculated. The values of the length of tangent vectors with 4 edges (P=1) adjacent to the vertex of Gaussian weave state ψp, as well as the angles between them, are also obtained in the cases of k=0 and k=2.
A study of the cross sections and the spin observables for proton-12C elastic scattering in momentum space in the intermediate energy region
Authors: Deng Yi-Bing  , Wang Shi-Lai  ,   浙江海洋学院物理系，舟山  316004
Published: December 2020

The differential cross sections and the spin observables of p-12C elastic scattering in the whole intermediate energy region are calculated using the KMT multiple scattering theory with microscopic momentum space optical potential which incorporates the spin dependence of the NN and p-12C interactions. The theory takes into consideration the antisymmetrized NN amplitudes, nucleon recoil and binding energy shifts, Lorentz invariant angle transformations, t matrices with on-shell behavior from NN phase shifts,and off-shell behavior from a realistic separable potential model. Qualitative agreement is found in differential cross sections and polarization data for 200Ep<1000 MeV.
Guassian soliton in biased photorefractive crystal
Authors: Chen Shou-Man  , Shi Shun-Xiang  , Dong Hong-Zhou  ,   (1)西安电子科技大学技术物理学院,西安 710071; (2)西安电子科技大学技术物理学院,西安 710071;安康学院光电子技术研究室,安康 725000; (3)西安电子科技大学技术物理学院,西安 710072
Published: December 2020

Using a variational approach, the low intensity photorefractive nonlinear Schr dinger equation is solved. The evolution properties of Guassian beam propagating in photorefractive crystal biased with positive electric field are obtained. The dynamic variation of the beam width spread or compression is investigated by analyzing the potential function description for the variation of beam width. Solutions of the low intensity Guassian beam propagating in the positively biased photorefractive crystal are obtained for the beam width, beam amplitude, and the curvature of wave front. The results show that the amplitude and width of Guassian beam will exhibit a periodical oscillatory or deconcentration behavior when propagating in the positively biased photorefractive crystal. Under certain condition, the Guassian beam can steadily propagate with invariant shape, forming a Guassian soliton. These properties have a high practical value in engineering.
Study of tunable terahertz-wave generation via difference frequency mixing in isotropic semiconductor crystals
Authors: Sun Bo  , Yao Jian-Quan  , Wang Zhuo  , Wang Peng  ,   天津大学精仪学院激光与光电子研究所,光电信息技术科学教育部重点实验室,天津 300072
Published: December 2020

The tunable, coherent terahertz wave generation in a variety of isotropic semiconductor nonlinear crystals, such as Ⅲ-Ⅴ and Ⅱ-Ⅳ compounds, by difference frequency mixing is studied theoretically based on the theory of the cross-Reststrahlen band dispersion compensation phase-matching. An angle-tuned, dual-wavelength KTP-OPO operating near the degenerate point is used as the pump source for THz wave generation. The theoretical analysis of phase-matching conditions and coherence length for different materials mentioned above is presented according to their optical dispersion properties, and their gain characteristic and nonlinear figure of merit are also described and calculated. Through the theoretical analyses and calculations, it is shown that ZnTe is a promising DFG crystal for THz wave generation under the collinear phase-matching condition, while InP is the one under the noncollinear phase-matching condition.
Theoretical investigation of propagation of nonlocal spatial soliton in nematic liquid crystals
Authors: Long Xue-Wen  , Hu Wei  , Zhang Tao  , Guo Qi  , Lan Sheng  , Gao Xi-Cun  ,   (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)华南师范大学光子信息技术广东省高校重点实验室,广州 510006;华南师范大学信息光电子科技学院传输光学实验室,广州 510006
Published: December 2020

In this paper, we investigate the propagation of the nonlocal optical spatial soliton in undoped nematic liquid crystals. On the basis of Schrdinger-type nonlinear equation and reorientation equation, we not only obtained the analytical expression of spatial soliton but also got the expression of breather in the vicinity of the critical power by use of Guassian trial solution. By comparisons of analytical and numerical simulations, we found that our expressions are more precise than those of C.Conti and G.Assanto. Furthermore,we thoroughly compare the nonlocal model in nematic liquid crystals with the linear model suggested by Snyder and Mitchell.
Study of rare-gas atom injection into defective carbon nanotube by molecular dynamics simulation
Authors: Jin Nian-Qing  , Teng Yu-Yong  , Gu Bin  , Zeng Xiang-Hua  ,   扬州大学物理科学与技术学院，扬州 225002
Published: December 2020

Based on the classical molecular dynamics method and using TLHT potential, the dynamic processes of rare-gas atom (He, Ne, Ar, Kr, Xe) injection into defective single-wall carbon nanotube (SWCNT) are investigated. The threshold energies of rare-gas atoms injected into a defective wall and absorbed on an open end of SWCNT are obtained and compared with the case of perfect SWCNT. It shows that the threshold energy Ek0 decreases with increasing of the defect size. When the defect radius is less than 4.5 ?，the rare-gas atoms with proper threshold energies can be encapsulated in SWCNT. But when the defect radius is over 4.5 ?，the rare-gas atoms can not be encapsulated in SWCNT, and the transport properties of Ar, Kr and Xe will change greatly.
Approximate analytical solutions for a class of nonlinear differential equations
Authors: Zheng Lian-Cun  , Feng Zhi-Feng  , Zhang Xin-Xin  ,   (1)北京科技大学机械工程学院,北京 100083; (2)北京科技大学数学力学系，北京 100083
Published: December 2020

This paper presents a theoretical analysis for a class of generalized diffusion equations. An effective analytical decomposition and numerical technique is given by similarity transformations and the analytical decomposition technique. The approximate analytical solution may be expressed in terms of a rapid convergent power series with elegantly computable terms. The reliability and efficiency of approximate solutions are illustrated by good agreement with numerical results.
Microstructure and mechanical properties of VN/SiO2 nanomultilayers synthesized by reactive sputtering
Authors: Yue Jian-Ling  , Kong Ming  , Zhao Wen-Ji  , Li Ge-Yang  ,   上海交通大学金属基复合材料国家重点实验室,上海 200030
Published: December 2020

VN/SiO2 nanomultilayers with different individual SiO2 and VN layer thicknensses were prepared with V and SiO2 targets by reactive sputtering. The microstructure and mechanical properties of the films have been studied by X-ray diffraction, energy dispersive X-ray spectrometry, high-resolution transmission electron microscopy and nanoindentation. The results reveal that the SiO2 film synthesized by radio frequency reactive sputtering in Ar-N2 gas mixture contains no N element, normally amorphous SiO2 is forced to crystallize at very low layer thickness (2 layer gradually forms an amorphous structure and blocks the coherent growth of nanomultilayers, and the hardness of nanomultilayers gradually decreases. On the other hand, the changing of VN layer thickness has relatively small effects on the microstructure and mechanical properties of nanomultilayers.
Effect of SiO2 crystallization on AlN/SiO2 nano-multilayers with superhardness effect
Authors: Zhao Wen-Ji  , Kong Ming  , Huang Bi-Long  , Li Ge-Yang  ,   上海交通大学金属基复合材料国家重点实验室,上海 200030
Published: December 2020

A series of AlN/SiO2 nano-multilayers with different SiO2 thickness were prepared by reactively magnetic sputtering. The microstructure of the nano-multilayers was characterized with X-ray diffraction and high-resolution transmission electron microscopy, and a nanoindentor was used to measure their mechanical properties. The phenomenon of crystallization of SiO2 in the multilayers and its effects on multilayer growth and mechanical properties were studied. Results show that SiO2, normally amorphous under sputtering condition, was crystallized when thickness was below 0.6 nm due to the effect of hcp crystal structure of AlN. And SiO2 formed a pseudocrystal structure just the same as AlN and grew epitaxially with AlN on the crystal plane of (0001). Because of the lattice mismatch between two layers, there existed an alternate stress field in the multilayer, which counted for a large portion of the hardness enhancement of the multilayer. Further increasing SiO2 layers thickness, the coherent interfaces of the multilayers were damaged and SiO2 become amorphous, accompanying by the decline in the hardness of the films.
Full-mode analysis of a two-dimensional photonic crystal waveguide
Authors: Yin Hai-Rong  , Gong Yu-Bin  , Wei Yan-Yu  , Lu Zhi-Gang  , Gong Hua-Rong  , Yue Ling-Na  , Huang Min-Zhi  , Wang Wen-Xiang  ,   电子科技大学物理电子学院,成都 610054
Published: December 2020

To determine the guide operating band, we derived the eigenvalue equations for a two dimensional photonic crystal rectangular waveguide, and found that the E(y), TEy, H(y) and TMy modes can exist in the photonic crystal rectangular waveguide. The calculation explains that this kind of waveguide can operate in single mode, if the height of the waveguide is low enough. And the bandwidth when the waveguide operates in single mode is determined by the cutoff frequency of the E(y)1 mode and that of the E(y)2 mode.
Study on optical properties of Er/Er+O doped GaN thin films
Authors: Song Shu-Fang  , Chen Wei-De  , Xu Zhen-Jia  , Xu Xu-Rong  ,   (1)北京交通大学光电子研究所，北京 100044; (2)北京交通大学光电子研究所，北京 100044;中国科学院半导体研究所，北京 100083; (3)中国科学院半导体研究所，北京 100083
Published: December 2020

We extend the use of Raman spectroscopy to investigate the modes of Er-implanted and Er+O co-implanted GaN, and discuss the influence of O ions on Er3+-related infrared photoluminescence (PL). It is found that Er3+ implantation introduces new Raman peaks in Raman spectra at frequencies 300 and 670 cm-1, and one additional new peak at 360cm-1 is introduced after Er+O implantation. It is proposed that the broad structure around 300 cm-1 mode originates from disorder-activated scattering (DARS). The Raman peak at 670 cm-1 is assigned to nitrogen vacancy related defects. The 360 cm-1 peak is attributed to the O implantation induced defect complexes (vacancies, interstitial, or anti-sites in the host). The appearance of the 360 cm-1 mode results in the decrease of the Er3+-related infrared PL of GaN:Er+O.
A double magneto-optical trap system using a slow atomic beam for atom transfer
Authors: Zhou Shu-Yu  , Xu Zhen  , Zhou Shan-Yu  , Wang Yu-Zhu  ,   中国科学院上海光学精密机械研究所量子光学重点实验室,上海  201800
Published: December 2020

A rubidium double magneto-optical trap(MOT) system for Bose-Einstein condensation experiments has been set up. A slow atomic beam has been obtained with a low-velocity intense source (LVIS) and used to transfer atoms into an ultra-high-vacuum (UHV) MOT. By maintaining a pressure difference of 3 orders between LVIS-MOT and UHV-MOT, a lowest pressure of 1×10-9Pa can be achieved in UHV-MOT. The flux of the slow atomic beam is 1×109/s. About 4×108 87Rb atoms can be loaded into UHV-MOT. In this paper, maximum number of atoms captured in MOTs under two typical conditions have also been discussed.
Performance of CdTe solar cells with different back electrodes and back contact layers
Authors: Song Hui-Jin  , Zheng Jia-Gui  , Feng Liang-Huan  , Cai Wei  , Cai Ya-Ping  , Zhang Jing-Quan  , Li Wei  , Li Bing  , Wu Li-Li  , Lei Zhi  , Yan Qiang  ,   (1)陕西科技大学材料科学与工程学院，咸阳 712081; (2)四川大学材料科学与工程学院，成都 610064
Published: December 2020

In this paper, the effects of Ni and Au back electrode on the performance of CdTe solar cells and the mechanisms have been studied by experiment. Among the back electrodes of Ni, Ni/Au, Au/Ni and Au film, only when the Ni film contacts the ZnTe/ZnTe:Cu complex layers, does the conversion efficiency increase with the short current increasing. So it is probable that the conversion efficiencies of cells will be increased by 4% at least, and the cost in large scale manufacturing will be cut down. By analyzing the dark C-V/I-V cures and the XPS using different back electrode films, it has been found the concentration and depth of Ni diffusion in the ZnTe/ZnTe:Cu back contact layer are greater than that of Au. What's more, most Nix+ combine with the abundant Te ions in ZnTe/ZnTe:Cu back contact layer to form the NixTe. So the diffusion concentration is increased, which makes the characters of CdTe improved.
Characteristics of degradation under GIDL stress in ultrathin gate oxide LDD nMOSFET’s
Authors: Chen Hai-Feng  , Hao Yue  , Ma Xiao-Hua  , Tang Yu  , Meng Zhi-Qin  , Cao Yan-Rong  , Zhou Peng-Ju  ,   西安电子科技大学微电子学院，西安 710071
Published: December 2020

The threshold voltage (VTH) degradation have been investigated under GIDL　(gate induced drain leakage) stresse in LDD nMOSFET with 1.4　nm-thick gate oxide. The trapped holes and interface states generated in the stress process at interface around LDD overlapping region result in the increase in VTH. The logarithm of VTH degradation after GIL stresses at constant VDG is proportional to the ratio of VD/VDG. The VTH degradation after GIDL stresses at constant VD increases with increasing VG in the stress, and that after GIDL stresses at constant VG increases with increasing VD in the stress In the last two cases the VTH degradation is always linear with the reciprocal of the bias which changes in the stress, and the absolute values of degradation slopes are 0.76 and 13.5, respectively. Experimental result shows that the degradation depends more strongly on VD than on VG.
Magnetic and magneto-optical properties of perpendicularly c-axis orientated FePt thin films
Authors: Wang Shu-Hua  , Zha Chao-Lin  , Gao Jing  , Ma Bin  , Zhang Zong-Zhi  , Jin Qing-Yuan  ,   复旦大学先进光子学材料与器件国家重点实验室，光科学与工程系，上海 200433
Published: December 2020

A series of FePt thin films with perpendicular c-axis orientation were deposited on single crystal MgO (001) substrates by DC magnetron sputtering. With the increase of substrate temperature during deposition, FCC disordered structure transforms to FCT ordered structure (L10 phase) gradually, and the chemical ordering parameter increases simultaneously. Furthermore, the magneto-crystalline anisotropy, coercivity and squareness ratio of the hysteresis loops along perpendicular direction increase also. The magneto-optical Kerr spectra were found to be changing notablely with the chemical ordering of FePt films.
The magnetic interactions in FePt nanocomposite film
Authors: Zhan Xiao-Yuan  , Zhang Yue  , Qi Jun-Jie  , Gu You-Song  , Zheng Xiao-Lan  ,   北京科技大学材料物理与化学系，北京 100083
Published: December 2020

Fe53Pt47 nanocomposite films have been deposited on naturally oxidized Si(100) substrates by magnetron sputtering. The relationship between the grain size, the magnetic interaction and the annealing temperature have been studied. The FePt films exhibit magnetically hard property with average grain size of about 20 nm after annealing at 400℃, and exchange spring behavior was found in the sample because it is composed of magnetically soft γ-FePt phase and hard γ2-FePt phase. As the annealing temperature increases, the content of the γ2-FePt phase increases, at the same time, the grain size gets large, and the exchange spring behavior in some particles was discoupled. The static magnetic interaction only occur between the FePt particles in the film annealed at 600℃.
Enhanced ferroelectricity of Pb(Zr0.5Ti0.5)O3 film by the introduction of La0.3Sr0.7TiO3 template layer
Authors: Wang Xiu-Zhang  , Liu Hong-Ri  ,   湖北师范学院生化分析技术湖北省重点实验室，湖北师范学院物理系，黄石 435002
Published: December 2020

LaNiO3(LNO) and LaNiO3/La0.3Sr0.7TiO3 (LNO/LSTO) bottom electrodes were prepared on Si(111) substrates by sol-gel process. Then Pb (Zr0.5Ti0.5)O3 (PZT) ferroelectric films were then deposited on the bottoms also by sol-gel process. XRD showed that both of the PZT films have perovskite structure. The one on LNO bottom adopts (100) preferred orientation and the one on LNO/LSTO bottom adopts random orientation. The results of ferroelectric measurement showed that the ferroelectricity of the PZT film on LNO/LSTO bottom electrode was substantially enhanced compare with the one on LNO bottom electrode. The coercive field was also enhanced. The film on LNO/LSTO bottom electrode has larger dielectric constant and leakage current.
Research on several parameters influencing on laser cooling of solids
Authors: Jia You-Hua  , Ji Xian-Ming  , Yin Jian-Ping  ,   (1)光谱学与波谱学教育部重点实验室，华东师范大学物理系，上海 200062; (2)光谱学与波谱学教育部重点实验室，华东师范大学物理系，上海 200062；南通大学理学院，南通 226007
Published: December 2020

Laser cooling of solids is also called anti-Stokes fluorescent cooling, it is a new optical cooling technology in recent years. We propose a two-level model to analyze the absorption and stimulated-emission processes between the Yb3+2F7/2 ground-state manifold and the 2F5/2 excited-state manifold, and discuss several parameters that influence the cooling power, and find some ways to improve the cooling power. The influences of the doped concentration, pumping power and the effective pump-spot area on cooling are particularly analyzed. At the same time, we make computer simulation about the cooling process and obtain the temperature as a function of the cooling time, which is similar to the experimental results. So this shows that our model is reasonable.
As-soak dependence of interface roughness of AlSb/InAs superlattice
Authors: Li Zhi-Hua  , Wang Wen-Xin  , Liu Lin-Sheng  , Jiang Zhong-Wei  , Gao Han-Chao  , Zhou Jun-Ming  ,   中国科学院物理研究所，北京 100080
Published: December 2020

Different As-soak time is applied during InSb-like interfaces growth of InAs/AlSb superlattices on GaAs(100) substrates. The interface roughness is studied by grazing incidence X-ray reflectivity. The reflectivity curves are simulated by standard software and the rms roughness of the interfaces is obtained. It was hown that the sample with As-soak time of 20 seconds has the most smooth interfaces. By analyzing the microscope images of the samples, we suggest that In-rich interfaces will be formed with too short As-soak time and AlAs-like interfaces are obtained with too long As-soak time, and in hoth cases the interface will be cearsened. Grazing incidence X-ray reflectivity is also recommended as a powerful tool for assessing the structure of superlattices.
The influence of different scale systems on precipitation analyzed on the basis of power-law exponent
Authors: Zhi Rong  , Lian Yi  , Feng Guo-Lin  ,   (1)吉林省气象科技研究所气候研究开放实验室，长春 130062; (2)吉林省气象科技研究所气候研究开放实验室，长春 130062；国家气候中心，中国气象局气候研究开放实验室，北京 100081; (3)扬州大学物理科学与技术学院，扬州 225009；中国科学院大气物理研究所东亚区域气候-环境重点实验室，北京 100029
Published: December 2020

Based on the daily precipitation observations of 740 stations in China from 1960 to 2000, this paper expounds the power-law tail distribution characteristic of the daily precipitation ≥30mm in 7 climate characteristic regions, and the power-law exponent γ>3.0 in most part of China. It is found that the daily precipitation ≥30 mm is a non-stationary process, and it makes the long-term prediction of heavy rainfall very difficult. It is also found from further investigation using the filtering method that the power-law tail distribution characteristic is the result of the interaction of atmospheric systems of various scales, among them the one-week scale system has the most important influence on power-law tail exponent of the daily precipitation ≥30 mm.
Electromagnetic scattering of plane wave/Gaussian beam by parallel cylinders
Authors: Wang Yun-Hua  , Guo Li-Xin  , Wu Zhen-Sen  ,   西安电子科技大学理学院,西安  710071
Published: December 2020

Based on the equivalence principle and the reciprocity theorem, the multiple scattering up to Nth-order by N parallel 2-D targets arbitrarily located in a plane wave/Gaussian beam is considered. The first-order solution can easily be obtained by calculating the scattered field from isolated targets. However, due to the difficulty in formulating the couple scattered field, it is almost impossible to find an exact analytical solution for the higher order scattered field. In order to overcome this difficulty, the composite scattering field is studied by employing the technique based on the reciprocity theorem and the equivalence principle and a surface integral solution up to Nth-order is obtained. To evaluate the ith order scattering field，only the i-1th order scattered field from scatterers and the equivalent surface electric and/or magnetic current density induced by the incident wave are required. Using the approach proposed in this paper, the bi- and mono-static scattering width of the incident field by parallel adjacent inhomogeneous plasma-coated conducting cylinders is calculated and the dependence of attenuation of the scattering width on the thickness of the coated layer, the electron number density, the collision frequency and the radar frequency is discussed in detail.
The exact solutions of a modified Volterra lattice
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

An expanded method for constructing nonlinear differential-difference equation is presented. With this method and computer algebra system Maple, many exact soluions of a modified Volterra lattice have been obtained. The method can also be used for other nonlinear differential-difference equations.
Solitons in a one-dimensional ferromagnetic chain under the influence of single-ion anisotropy
Authors: Weng Zi-Mei  , Chen Hao  ,   华南师范大学物理与电信工程学院，广州 510006
Published: December 2020

Cnoidal wave solutions and soliton solutions in a one-dimensional ferromagnetic chain with anisotropy exchange interaction and single-ion anisotropy are obtained through travelling wave solution method and the influence of single-ion anisotropy on cnoidal waves and solitons is discussed. The results indicate that single-ion anisotropy makes the cnoidal waves and solitons easy to excite in an easy-plane ferromagnetic chain but difficult in an easy-axis one, and makes them more stable in the easy-axis ferromagnetic chain but less stable in the easy-plane one. The influence of single-ion anisotropy on soliton excitations in a one-dimensional isotropic ferromagnet is also discussed.
Transversal optical vortex in the interference field of two off-axis Gaussian beams
Authors: Wang Li  , Wang Qing-Feng  , Wang Xi-Qing  , Lü Bai-Da  ,   (1)四川大学 激光物理与化学研究所，成都  610064; (2)西南交通大学峨眉校区，峨眉  614202; (3)西南交通大学理学院物理系，成都  610031
Published: December 2020

The structure of the wavefront and transversal optical vortices in an interference field of two off-axis Gaussian beams is studied. It is shown that the positions of phase saddles and vortices depend on the off-axis parameter, beam width, phase and relative amplitude of beams. The saddle can be located inside or outside the vortices. For a certain value of the governing parameter, the saddle point coincides with the vortex. For off-axis beams, the encounters of the saddle point and vortex on both sides in the XZ cross-section do not occur at the same governing parameter η. Moreover, the x value corresponding to the encounter of saddle points is not equal to the x value corresponding to the encounter of vortices.
Research on the growing process of short message networks
Authors: Wu Ye  , Xiao　Jing-Hua  , Wu Zhi-Yuan  , Yang Jun-Zhong  , Ma Bao-Jun  ,   (1)北京邮电大学理学院，北京 100876; (2)中国联合通信有限公司北京分公司，北京 100038
Published: December 2020

We investigate the growing process and topological features of the short message networks (SMN). Simulations show that the networks' degree distribution，average degree and the correlation between the node's degree and its time in the network are different from those of the former networks models. With due consideration of some of the characteristics of the SMN, we suggest a new type of network growing protocol,namely the local-preference connecting protocol. The numerical results show that the networks generated from our model are more representative in simulating real networks represented by SMN when compared with other network models.
Nondipole effects in high-order harmonic generation induced by extreme ultraviolet attosecond pulse
Authors: Zheng Ying-Hui  , Zeng Zhi-Nan  , Li Ru-Xin  , Xu Zhi-Zhan  ,   (1)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; (2)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;中国科学院研究生院，北京 100049
Published: December 2020

When intense infrared laser and extreme ultraviolet (XUV) attosecond pulse interact with an atom or molecule, the released electrons generally suffer a spread of energies due to the absorption and emission of laser photons. The nondipole effects in the high-order harmonic generation caused by the short wavelength of XUV attosecond pulse which is comparable to the scale of spreading electron wavepacket are discussed in this paper. The H+2 ion as a model molecule is assumed to be aligned along the propagation direction of the laser field. By solving the two-dimensional time-dependent Schrdinger equation and comparing the results taking account of nondipole effects with those under the dipole approximation, we find that intensity of the former harmonic yield is lower than that of the latter with a shift of the frequency towards lower order harmonics, and that more photoelectron peaks appear in the energy band of the photoelectron spectrum and the difference of their signal intensity at the same photoelectron energy is 2—5-fold. The results of numerical simulation also show that the nondipole effects are enhanced with the infrared laser field strength increasing and are weakened with the wavelength of attosecond pulse increasing.
Effect of initial frequency chirp on the linear propagation characteristics of the hyperbolic secant optical pulse
Authors: Zheng Hong-Jun  , Liu Shan-Liang  , Li Xin  , Xu Jing-Ping  ,   (1)华中科技大学电子科学与技术系，武汉 430074; (2)华中科技大学电子科学与技术系，武汉 430074;聊城大学光通信研究所，聊城 252059; (3)聊城大学光通信研究所，聊城 252059
Published: December 2020

The linear propagation characteristics of the hyperbolic secant optical pulse with initial linear and nonlinear frequency chirps are numerically studied in the anomalous-dispersion regime of a single mode fiber by use of the split-step Fourier method. It is found that the linear chirped hyperbolic secant pulse gradually evolves into near Gaussian pulse for |C|>0.1, and evolves into near hyperbolic secant pulse for 0≤|C|≤0.1. The smaller |C| is, the more the waveform approaches to hyperbolic secant curve. The effect of the negative linear chirp on the pulse broadening is greater than that of the positive chirp. The effect of the initial linear chirp on broadening of hyperbolic secant pulse is greater than that of Gaussian pulse for |C|≥0.5. The temporal waveform splitting of the hyperbolic secant pulse with nonlinear chirp is more obvious than that of Gaussian pulse during linear propagation. Furthermore, the expression of the time-bandwidth product of the pulse with the linear chirp is given.
First-principles study on the microarrangement of Al and structure and elasticity of LaNi3.75Al1.25
Authors: Zhou Jing-Jing  , Gao Tao  , Zhang Chuan-Yu  , Zhang Yun-Guang  ,   四川大学原子与分子物理研究所，成都 610065
Published: December 2020

The density functional theory on the level of generalized gradient approximation and full-potential linearized augmented plane wave, and the two-dimensional cubic fitting method have been used to calculate the geometrical and elastic property of LaNi3.75Al1.25 compound. The results indicate that the substitutional Al atoms in this compound are most likely to occupy part of the equivalent positions of 3g and 2c. The optimized lattice parameters a=b=0.5137 nm，c=0.4018 nm, the elastic constants C11+C12=281.2, C13=82.3, C33=227.3, the bulk modulus B＝124.5 and shear modulus G＝68.2 GPa have also been worked out. The density of state, band structure and charge density have been presented, and the electronic specific heat 23.45 mJ/molK2 for LaNi3.75Al1.25 has been estimated.
Projective synchronization of autonomous chaotic system based on linear separation
Authors: Wang Xing_Yuan  , Wang Yong  ,   大连理工大学电子与信息工程学院，大连 116024
Published: December 2020

This paper analyses the projective synchronization in autonomous chaotic system. Base on the stability criterion of linear systems, a new approach for constructing chaotically projective synchronization is proposed. The projective synchronizations of Lorenz system, Rssler system and hyperchaotic chen's system are achieved via the linear separation method. Numerical simulations are provided for illustration and verification of the proposed method.
The mean first-passage time for an asymmetric bistable system driven by multiplicative and additive noise with colored correlations
Authors: Ning Li-Juan  , Xu Wei  , Yang Xiao-Li  ,   (1)西北工业大学应用数学系，西安  710072; (2)西北工业大学应用数学系，西安  710072；陕西师范大学数学与信息科学学院，西安  710062
Published: December 2020

In this paper,the effects of colored correlations and asymmetry of the potential on the mean first-passage time(MFPT) are investigated for an asymmetric bistable system driven by multiplicative noise and additive noise.Numerical results show that the intensities of multiplicative and additive noises and the cross-correlation time τ affect the MFPT in the same way,the coupling strength λ and asymmetry r of the potential affected the MFPT in the same way.The increase of τ enhances the escape rate,while increase of λ reduces the escape rate.
Dispersion and localization of defect state in one-dimensional photonic crystal consisting of metamaterials
Authors: Dong Jian-Wen  , Chen Yi-Hang  , Wang He-Zhou  ,   中山大学光电材料与技术国家重点实验室，广州  510275
Published: December 2020

The expressions of the dispersion relationship and space localization in the one-dimensional photonic crystal (1DPC) with symmetric semi-infinite period number and a central defect layer are deduced, which are valid for the defect 1DPC consisting of materials with arbitrary frequency-dependence. Based upon them, we found that the eigenfrequency of defect state is red-shifted with the increasing geometry thickness of defect layer in right-handed materials. On the contrary, the frequency is blue-shifted when the defect layer is a left-handed material. Moreover, the defect state is more localized for symmetric semi-infinite period structures consisting of metamaterials than those of conventional right-handed materials.
The study of two-dimensional composite materials with wide band gap
Authors: Li Xiao-Chun  , Liang Hong-Yu  , Yi Xiu-Ying  , Xiao Qing-Wu  , Zhao Bao-Xing  ,   中南大学物理科学与技术学院，长沙 410083
Published: December 2020

Using FDTD method, the characteristics of elastic/acoustic wave propagating in two dimensional phononic crystals (PCs) consisting of Fe square arrayed cylinders in water was investigated. The absolute band gap was found in high frequency range for Fe/water structure, and the resonance gap was found in low frequency range for coated Fe/water structure, where the Fe cylinders were softly coated by rubber. These two gaps correspond to different mechanisms. Constructed with these two kinds of PCs, a combined wide gap from high to low frequency can be achieved, so the elastic wave propagating can be prohibited in a wide frequency range. Furthermore, the combined wide band gap can be adjusted effectively through changing the structure parameters, such as the size of Fe core, thickness of coating layer, filling ratio etc.