bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermodynamic properties of a weakly interacting Fermi gas in weak magnetic field
Authors: Men Fu-Dian  ,   中国石油大学(华东)物理科学与技术学院，东营  257061
Published: December 2020

The analytical expressions of internal energy, chemical potential and heat capacity of the little parameter r for a weakly interacting Fermi gas in weak magnetic field are derived by using “pseudopotential" method and ensemble theory. Based on the derived expressions, the thermodynamic properties of a weakly interacting Fermi gas in weak magnetic field at both high and low temperatures are given. The effects of magnetic field and interparticle interactions on the thermodynamic properties are discussed. The difference in the effects of magnetic trap and three-dimensional harmonic trap on the properties of the system and their reasons are analyzed.
Approximate entropy analysis of current in short-circuiting arc welding
Authors: Cao Biao  , Lü Xiao-Qing  , Zeng Min  , Wang Zhen-Min  , Huang Shi-Sheng  ,   华南理工大学机械工程学院，广州  510640
Published: December 2020

Based on the approximate entropy theory and related algorithm, approximate entropy analysis of current in short-circuiting arc welding in CO2 shielding gas are performed from the point of view of nonlinear time sequences. Calculation and comparison of approximate entropy of current under different wire-feeding speeds, setting voltages and different gas flow rates show that approximate entropy of current can be taken as a creterion of stability of short-circuiting transfer. The results show that greater approximate entropy and less fluctuation indicate a more stable welding process.
Controllable four-well optical trap for cold atoms or molecules
Authors: Lu Jun-Fa  , Ji Xian-Ming  , Yin Jian-Ping  ,   (1)华东师范大学物理系，光谱学与波谱学教育部重点实验室，上海  200062; (2)华东师范大学物理系，光谱学与波谱学教育部重点实验室，上海  200062;东华理工学院物理系，抚州  344000; (3)华东师范大学物理系，光谱学与波谱学教育部重点实验室，上海  200062;南通大学物理系，南通  226007
Published: December 2020

In this paper, we propose a novel scheme to build a controllable four-well optical trap for cold atoms or molecules by using an optical system of a binary π-phase plate and a lens illuminated by a plane light wave. We calculate the intensity distribution of the four-well optical trap, and discuss the evolution process of the optical trap from four wells to two wells or form four wells to a single well, and derive some analytical relations between the characteristic parameters of the four-well trap (including geometric parameters, intensity distribution, intensity gradients and their curvatures) and the parameters of the optical lens system. Our study shows that our four-well trap can be continuously changed into a double-well one or a single-well one by moving the π-phase plate, and the relation between the distance of the trapping centers of the four wells or two wells and the moving distance of the π-phase plate is obtained by data fitting. So our four-well trap scheme has important and wide potential aplications in the fields of ultracold atomic physics, cold molecular physics, atom optics, molecule optics and quantum optics,and even in the fields of quantum calculation and information processing, and so on.
Entropy evolution of field interacting with two entangled-atoms
Authors: Huang Chun-Jia  , He Hui-Yong  , Zhou Ming  , Fang Jia-Yuan  , Huang Zu-Hong  ,   长沙理工大学物理与电子科学系，长沙  410076
Published: December 2020

The entropy evolution of the field interacting with two entangled-atoms are studied by means of quantum theory.Using the numerical method,the influence of the entanglement of atoms and the intensity of field on the entropy evolution of the field is discussed. The results show that the entanglement of atoms affects the mean-value of field entropy and the intensity of field affects the oscillation properties of field entropy evolution.
Phonon mediated electromagnetically induced transparency and ultraslow light in strongly coupled exciton-phonon systems
Authors: Yao Ming  , Zhu Ka-Di  , Yuan Xiao-Zhong  , Jiang Yi-Wen  , Wu Zhuo-Jie  ,   (1)宁夏大学物理电气信息学院,银川  750001; (2)上海交通大学物理系,上海  200030
Published: December 2020

Phonon mediated electromagnetically induced transparency(EIT)and ultraslow light in strongly coupled exciton-phonon systems are investigated theoretically without making any approximation for excitons. It is shown that electromagnetically induced transparency mediated by phonons and the ultraslow light can occur in such systems as the signal field detuning from the exciton frequency is exactly equal to the phonon frequency. It is further shown that the phonon mediated EIT and ultraslow light calculated by using the exact exciton model is essentially the same as the numerical results obtained using the Bose approximation or the Dyson-Maleev approximation.
Hydrogen bonding configurations and energy band structures of hydrogenated nanocrystalline silicon films
Authors: Yu Wei  , Zhang Li  , Wang Bao-Zhu  , Lu Wan-Bing  , Wang Li-Wei  , Fu Guang-Sheng  ,   河北大学物理科学与技术学院，保定  071002
Published: December 2020

The correlation between the hydrogen bonding configurations and the energy band structures of hydrogenated nanocrystalline (NC) silicon films has been investiga ted. The samples were prepared by helicon wave plasma chemical vapor deposition technique. Raman scattering, infrared absorption and optical absorption measurem ents were used to analyze the microstructure, hydrogen bonding configurations an d energy band structures of the deposited films. Raman results indicate that dis tinct different structures appear in films deposited at various substrate temper atures and there is a threshold at about 200℃ for the amorphous silicon to be t ransformed to the NC phase. The energy band structures of the films are closely related to their hydrogen bonding configurations. The chemical shift of the vala nce band to the lower state induced by high hydrogen content and the structural disorder related to low substrate temperature makes the films have wide band gap s and large band tail widths. With increasing the substrate temperature, the dec rease trend of optical band and tail width is mainly related to the enrichment o f the hydrogen located in the grain boundary, which perform the function of term inating the dandling bonds at NC silicon grain surface. Further increasing the s ubstrate temperature broadens the band tail width of the films because the hydro gen content is too low to passivate the dangling bonds at the NC silicon grain s urface.
Spectrum structure and g factor of electron paramagnetic resonance of LiCoO2 crystal doped with Ni
Authors: Yang Liu  , Yin Chun-Hao  , Jiao Yang  , Zhang Lei  , Song Ning  , Ru Rui-Peng  ,   中国矿业大学理学院，徐州  221008
Published: December 2020

In the weak field scheme, the complete diagonalizing Hamiltonian matrices and th e constants of crystal structure and g factor of electron paramagnetic resonanc e are derived for 3d4/3d6 ions configuration in the trigon al symmetry in terms of Racahs irreducible tensor operator method. The ground- state energy levels and the constants of crystal structure and g factor of elec tron paramagnetic resonance of the Co3+ in LiCoO2 and LiCo O2:Ni crystals are studied. The spin singlets and triplet of the grou nd-state energy levels of the Co3+ in LiCoO2 and LiCoO2:Ni crystals are taken into consideration in the calculation and applica tion of the crystal-field energy of 3d4/3d6. The changes o f the constants of local structure, which are the causes of the changes of the g round-state energy levels of the Co3+, and the values of g factor of electron paramagnetic resonance of Co3+ in LiCoO2 and LiCo O2:Ni crystals are also studied. The theoretical results are in good agreement with the experimental observations.
Preparation and thermoelectric properties of Ti1－x(Hf0.919Zr0.081)xNiSn
Authors: Liu Hai-Qiang  , Tang Xin-Feng  , Wang Kun  , Song Chen  , Zhang Qing-Jie  ,   武汉理工大学材料复合新技术国家重点实验室,武汉  430070
Published: December 2020

Single-phase Ti1-x(Hf0.919Zr0.081)xN iSn (x＝0.00—0.15) compounds were synthesized by solid-state reaction and high- density polycrystalline bulk material was prepared by spark plasma sintering (SP S). The effect of Hf and Zr substitution for Ti on the thermoelectric propertie s of TiNiSn half-Heusler compounds were investigated. It was shown that the subs titution of a small amount Hf and trace Zr for Ti resulted in significant reduct ion of the thermal conductivity and remarkable enhancement of the Seebeck coeff icient. As a result, the dimensionless figure of merit ZT of Ti0.85(H f0.919Zr0.081)0.15NiSn reached a high maximum v alue of 0.56 at 700K and the enhancement of ZT was 190%—310% at the same temper ature compared with ternary TiNiSn compounds.
Abnormal Raman spectra of PbTe crystalline thin films grown by molecular beam epitaxy
Authors: Cao Chun-Fang  , Wu Hui-Zhen  , Si Jian-Xiao  , Xu Tian-Ning  , Chen Jing  , Shen Wen-Zhong  ,   (1)上海交通大学物理系，上海  200030; (2)浙江大学物理系，杭州  310027
Published: December 2020

High quality single crystalline PbTe thin films have been grown on BaF2(111) by using molecular beam epitaxy(MBE).Raman scattering measurements have revealed the vibration modes of oxide on the surface，longitudinal optical(LO) p honon at Brillouin center q≈0，and coupled plasmon-phonon.With the variation of the focusing-depth(FD) of the pumping laser beam，the integrated intensities，p eak positions and line widths of the observed Raman peaks showed different behav iors.When FD changed from 3μm above the top-surface to 3μm below the bottom-su rface, the PbTe LO phonon frequency shifted from 119 to 124cm-1.Diffe rent Raman scattering results were also observed by comparison of the freshly su rface-etched and the as grown PbTe samples. These phenomena originated from the different vibration modes. The frequency shift of LO phonon is explained by the fact that the strain relaxation caused by the lattice mismatch between PbTe and BaF2 is as high as 4.2％.
Nonequilibrium dynamic phase transition in a kinetic Ising spin system
Authors: Shao Yuan-Zhi  , Zhong Wei-Rong  , Lu Hua-Quan  , Lei Shi-Fu  ,   中山大学光电材料与技术国家重点实验室，广州  510275;中山大学物理系，广州  510275
Published: December 2020

We studied within the framework of a mean-field approach the nonequilibrium dyn amic phase transition of a kinetic Ising spin system subject to a perturbative f ield and temperature simultaneously by comparison between time-dependent Ginzbur g-Landau and Glauber dynamics models. The dynamic phase transition (DPT) boundar ies, separating a symmetry-breaking dynamic ordered phase from its symmetric dyn amic disordered counterpart, were identified through a systematic simulation of the above two models. The dependence of the dynamic order parameter Q and the fo urth order cumulant ratio U upon the temperature t(r0), the frequency ω and amplitude h0 of driving field were also investigated in detai l. A discussion was presented concerning the current controversies on whether bo th a discontinuous dynamic phase transition occurs possibly below a specific low temperature and a tri-critical point exists on the DPT boundary in a kinetic Is ing spin system.
Nonextensive thermostatistical investigation of free electronic gas in metal
Authors: Wang Can-Jun  , Wang Xiao-Feng  ,   (1)云南大学物理系非线性复杂系统中心，昆明  650091; (2)云南大学物理系非线性复杂系统中心，昆明  650091；宝鸡文理学院物理系，宝鸡  721007
Published: December 2020

The relevant aspects of the q-thermostatistical treatment for the free electronic gas which is an ideal Fermi system are discussed.Thermodynamical quantities of the free electronic gas such as total number of particles,total energy,heat capacity,free energy,etc.,are calculated within the Tsallis thermo-statistics where the factorization approach is incorporated,and the ensuing statistics is derived.Special attention is paid to heat capacity.The limiting cases of interest are discussed in some detail,namely,low-temperature regimes,and the approximate results pertaining to the case q→1 (the conventional Fermi-Dirac statistics corresponds to q=1).We also compare our results with previous Tsallis' works.
A simulation study for the effects of cooling rate on evolution of microstructures during solidification of liquid metal Ga
Authors: Zhang Hai-Tao  , Liu Rang-Su  , Hou Zhao-Yang  , Zhang Ai-Long  , Chen Xiao-Ying  , Du Sheng-Hai  ,   湖南大学应用物理系，长沙  410082
Published: December 2020

A simulation tracing study has been performed for the effects of different cooling rates on the evolution of microstructures during solidification process of liquid metal Ga by means of molecular dynamics method. The bond-types and basic cluster structures of metal Ga have been analyzed by using HA bond-type index method and cluster-type index method. It has been found that the cooling rate plays an important role to the microstructures in the solidification processes. At the cooling rates of 1.0×1014 K/s, 1.0×1013 K/s and 1.0×1012 K/s, the amorphous structures would be formed in the system with the rhombohedron related to 1311, 1301 bond-types as the main body, and coexist with the fcc, hcp and other structures; at the cooling rate of 1.0×1011K/s, crystallization would take place in the system, the crystalline transition temperature Tc being about 198K, and the lower the cooling rate, the higher the Tc. The crystal would have the orthorhombic structure related to 1421 bond-type(determined by visualized method) as the main body. This gives us a new way for researching the crystalline transition processes of liquid metals.
Characteristics of CdTe solar cell device
Authors: Yang Xue-Wen  , Zheng Jia-Gui  , Zhang Jing-Quan  , Feng Liang-Huan  , Cai Wei  , Cai Ya-Ping  , Li Wei  , Li Bing  , Lei Zhi  , Wu Li-Li  ,   四川大学材料科学系，成都  610064
Published: December 2020

For increasing the efficiency of CdTe/CdS solar cells, it is important to measure the current-voltage and capacitance-voltage characteristics and then carry out a numerical simulation based on electronic measurement of CdTe and CdS thin films. In this paper, the capacitance-voltage characteristics were measured in the frequency range from 50kHz to 1MHz. The carrier concentrations of the absorber layer and the space charge region width were calculated. The dark current-voltage characteristics of the CdTe solar cell were measured in the temperature range from 220K to 300K. The saturated reverse dark current density J0 and the diode ideal factor A of the solar cells were obtained. The relations of J0 and A with temperature were discussed. The results show that the capacitance-voltage curves has two peaks and the intensities and positions of the peaks are dependent on measurement frequency. The results are simulated and explained with the multi-junction model. With decreasing temperature, the saturated reverse dark current decreases from 10-6mAcm-2 at room temperature to 10-7mAcm-2 at 220K, and the diode ideal factor rises from 2.13 at room temperature to 9.95 at 220K.
The influence of (Ni0.81Fe0.19)1－xCrx seed layer on the exchange bias of NiFe/PtMn bilayers
Authors: Li Yan  , Chen Qing-Yong  , Jiang Hong-Wei  ,   首都师范大学物理系，北京  100037
Published: December 2020

By adjusting the Cr concentration, the effect of texture and grain size on the exchange bias of NiFe/PtMn bilayers with (Ni0.81Fe0.19)1-xCrx seed were systematically investigated. After annealing the bilayers at 270℃ for 5h, it was found that the difference in the texture of PtMn layer is not the cause of the variation in the exchange bias field. The exchange bias field depends strongly on the grain size of PtMn layer. When the grain size is around 11.3nm, the exchange field attains its maximum.
Effect of Pb, Ga doping on magneto-optical propertics of Ce:YIG crystal
Authors: Zhang Guo-Ying  , Cheng Yong  , Zhang Xue-Long  , Xia Tian  , Xue Liu-Ping  ,   (1)上海理工大学医疗器械学院，上海  200093; (2)中国矿业大学理学院，徐州  221008
Published: December 2020

The effects of Pb, Ga doping on the crystal field, superexchange interaction and magneto-optical effect of Ce:YIG crystal are studied based on the quantum theory. It is found that when the molecular concentration of Ga doping is 12%, the molecular field on the Ce3+ ion is reduced by 51% and the difference of occupation probability between the two lowest energy levels of the Ce3+ is reduced by 49%. The Ga doping affects the crystal field and molecular field at the same time, while the Pb doping affects the crystal field only.
Singular value decomposition and adaptive noise reduction for SQUID-based magnetocardiograms
Authors: Bai Yun  , Liu Xin-Yuan  , He Ding-Wu  , Ru Hong-Yu  , Qi Liang  , Ji Min-Biao  , Zhao Wei  , Xie Fei-Xiang  , Nie Rui-Juan  , Ma Ping  , Dai Yuan-Dong  , Wang Fu-Ren  ,   (1)北京大学物理学院，人工微结构和介观物理国家重点实验室，北京  100871; (2)北京大学信息科学技术学院，北京  100871
Published: December 2020

This paper shows that the environmental noise in the HTc rf-SQUID-based quasi-periodic magnetocardiograms (MCGs) can be reduced by singular value decomposition (SVD) and adaptive filtering without the reference channel input. Numerical simulation studies indicate that the method is an effective noise suppresser for one channel MCGs.
Hawking radiation of Dirac particles in an arbitrarily accelerating charged dynamic black hole
Authors: Cao Jiang-Ling  ,   北京师范大学物理学系，北京  100875;重庆三峡学院物理与电子工程学院，重庆  404000
Published: December 2020

In this paper, the four coupling Dirac equations are predigested in two coupling Dirac equations by choosing null tetrad and calculating rotation coefficients in the arbitrarily accelerating charged dynamic space time.Moreover, after change these two coupling equations into Tortoise coordinate system forms and get the classical wave equations near the event horizon of black hole,the authors educe the formulation of Howking thermal spectrum successfully and obtain the Hawking radiation temperature of Dirac particles near the event horizon.
Global synchronization of a class of chaotic neural networks
Authors: Wang Zhan-Shan  , Zhang Hua-Guang  , Wang Zhi-Liang  ,   (1)东北大学信息科学与工程学院, 沈阳  110004; (2)东北大学信息科学与工程学院, 沈阳  110004;沈阳理工大学信息工程系,沈阳  110168
Published: December 2020

This paper deals with the global asymptotic synchronization problem for a class of chaotic neural networks with delay. Using the drive-response conception and linear matrix inequality technique, two sufficient conditions are derived to guarantee the global synchronization of two chaotic neural networks with identical structure and different initial conditions, which also present a procedure to construct a synchronization controller. The controller gain can be achieved by solving a linear matrix inequality, and therefore, it is easily implemented in practice. Two illustrative examples are used to demonstrate the effectiveness of the proposed method.
Estimation method of high-reflecting region of periodic layered media
Authors: Zheng Kui-Song  , Ge De-Biao  ,   西安电子科技大学理学院,应用物理系,西安  710071
Published: December 2020

A concise method of estimating high-reflection range for layered media composed of finite periodic unit is presented. Based on the Floquet theorem, the photonic bandgap properties of periodic layered media are analyzed, and the wavelength range of high-reflection region for periodic layered media is discussed. The relation between high-reflection region of layered media and forbidden band of the periodic unit is discussed. Numerical results show that the center wavelength of high-reflection region coincides with the one of the forbiddan band of periodic unit. Furthermore, as the periodic unit number of layered media is increased, the depth and width of high-reflection region become close to those of forbidden band of the periodic unit. Finally, the variations of photonic bandgap properties of periodic layered media with respect to the incidence angle and polarization have also been discussed.
Phase transition of xPMnS-(1－x)PZN ceramics
Authors: Zhou Jing  , Zhao Ran  , Chen Wen  ,   武汉理工大学材料科学与工程学院，武汉  430070
Published: December 2020

The phase transformation of xPMnS-(1-x)PZN quaternary piezoelectric ceramics was studied and the effect of composition on phase transformation characteristics was also discussed. Results indicate that xPMnS-(1-x) PZN ceramics show disperse phase change characteristic and obvious dielectric thermal lag in the course of the phase change. The result of electronic structure investigation indicates that the disperse phase change should be attributed to the difference in strength of B—O bonds. The material has relaxation ferroelectric characteristics When x value is large (or small), and shows relatively strong disperse phase change. It has normal-relaxation ferroelectric characteristics when x value is near 0.4, and shows relatively weak disperse phase change.
First-principles calculations of electronic structure and magnetism of Gd2Co2Al
Authors: Zhang Jia-Hong  , Liu Su  , Gu Fang  , Yang Li-Juan  , Liu Mei  ,   (1)东南大学物理系,南京  210096; (2)南京理工大学理学院,南京  210094
Published: December 2020

We investigate the electronic and magnetic properties of the new compound Gd2Co2Al by using a self-consistent full-potential linearized augmented plane-wave method within the local spin-density approximation (LSDA) and the LSDA+U approximation to the exchange-correlation potential of the spin-density functional theory. We have also discussed the reason of system to have low Curie temperature, and made use of the average field theory to calculate the Curie temperature in combination with the results of density functional calculation. Our calculation shows that this system is a metallic conductor. The local Gd magnetic moment provides predominately the strong ferromagnetism and the Co-site local moment is unstable. Gd2Co2Al is shown to be a ferrimagnetic phase due to the moment of Gd sublattice being aligned antiparallelly to the Co moment in the LSDA. After considering the on-site Coulomb interaction by an additional Hubbard parameter U, it is found that the ground state becomes ferromagnetic at a moderate value of U (3.0eV), with a Co ion magnetic moment of 0.024μB, which is in good agreement with experiment. The moment of Co changes much and the density of states of Gd and Co are significantly redistributed with the change of U, while the magnetic moment of Gd does not change much. The competition of 5d-3d hybridization and the on-site Coulomb interaction leads to the fluctuation of the moment of Co.
Characterization of crystal lattice constant and strain of GaN epilayers with different AlxGa1－xN and AlN buffer layers grown on Si(111)
Authors: Ding Zhi-Bo  , Yao Shu-De  , Wang Kun  , Cheng Kai  ,   (1)MCP/ART,IMEC,Kapeldreef 75,B-3001 Leuven,Belgium; (2)北京大学物理学院,北京  100871
Published: December 2020

Hexagonal GaN epilayers with different AlxGa1-xN and AlN buffer layers were grown on Si(111) by metal-organic vapor phase epitaxy (MOVPE). Under the same growth conditions, the sample with four AlxGa1-xN buffer layers and one AlN buffer layer were grown on Si(111). According to the results of Rutherford backscattering (RBS)/channeling along axis, the conventional θ—2θ scans normal to GaN(0002) and (1122) plane at 0° and 180° azimuthal angles, and the reciprocal-space X-ray mapping (RSM) on GaN(1015) plane, we obtained that the crystal quality of the GaN epilayer is perfect with χmin＝1.54%. The crystal lattice constant of AlN, AlxGa1-xN and GaN epilayer has been calculated accurately, the lattice constant of GaN epilayer is almost equal to the theoretic data (aepi=0.31903nm, cepi=0.51837nm). The tetragonal distortion along the depth can got clearly from elastic strains of each layer in the normal and parallel directions, and the tetragonal distortion of GaN epilayer is nearly fully relaxed(eT=0).
A theoretical study of electrical properties of molecular junction
Authors: Li Ying-De  ,   潍坊学院物理与电子科学系，山东潍坊  261061
Published: December 2020

Basing on first principls, we investigate the electrical properties of a molecular junction consisting of 2-amino-5-nitro-1,4-diethyny-4’-benzenethiol-benzene molecule and gold surface. Density functional theory is employed to obtain the electronic structures of the molecule and the extended molecule. Then we determine the interaction energy between the molecule and the gold surface quantitatively. The elastic Green function method is applied to study its current-voltage properties. Numerical results show that when the external applied bias is lower than 0.9V, there is a current gap. With increasing bias, the conductance of the junction exhibits plateaus. These electrical properties are closely related to the electronic structures of the molecular junction. The extended molecular orbits have great contribution to the charge transport, while localized molecular orbits contributes but little to the current where charge transport takes place by tunneling.
Theoretical description and numerical computation of the relaxation of multi-spin system in the presence of an RF field
Authors: Xu Feng  , Liu Tang-Yan  , Huang Yong-Ren  ,   (1)安徽理工大学数理系,淮南  232001; (2)教育部光谱学与波谱学重点实验室，华东师范大学物理系,上海  200062; (3)中国石油勘探开发研究院测井与遥感技术研究所，北京  100083
Published: December 2020

According to the Liouville-von Neumann equation and WBR theory, a general description of relaxation of multi-spin system in the presence of an RF field is given. The relaxation equations are deduced and the theoretical computational formulas of various relaxation rates are obtained. It is almost impossible to accessthe analytical solutions of relaxation equations, so the computer program for numerical solutions is developed. By means of the program and the Bloch equations, the steady state solutions of two-spin system under various conditions are computed and these solutions are briefly discussed.
Crystallization of amorphous bismuth titanate
Authors: Xu Guo-Cheng  , Pan Ling  , Guan Qing-Feng  , Zou Guang-Tian  ,   吉林大学材料科学与工程学院，超硬材料国家重点实验室,长春  130025
Published: December 2020

The phase transformation of amorphous bismuth titanate fabricated by sol-gel method was investigated by X-ray diffraction (XRD), transmissions electron microscopy (TEM) and differential thermal analysis (DTA). The experimental results show that the four-step crystallizations were present on heating. The metastable phases Bi2O3 and TiO2 were formed firstly at 433℃, and Bi2Ti4O11 phase was subsequently formed at 488℃ by the reaction between Bi2O3 and TiO2. Sequential reaction between Bi2Ti4O11 and Bi2O3 resultedin the formation of Bi4Ti3O12 phase with tetragonal structure at about 644℃, and stable Bi4Ti3O12 phase with orthorhombic structure was finally formed at about 830℃.
Ferroelectric properties of Sr2Bi4Ti5O18 thin films prepared by sol-gel method
Authors: Fang Hong  , Sun Hui  , Zhu Jun  , Mao Xiang-Yu  , Chen Xiao-Bing  ,   (1)扬州大学物理科学与技术学院,扬州  225002; (2)扬州大学物理科学与技术学院,扬州  225002;南京大学固体微结构物理实验室,南京  210008
Published: December 2020

High quality Sr2Bi4Ti5O18 (SBTi) ferroelectric thin films on Pt/Ti/SiO2/Si(100) substrates were successfully prepared using the sol-gel method.The microstructure, ferroelectric properties and fatigue characteristics of SBTi thin films were investigated.The results show that the films with smooth surface are of single phase of SBTi and randomly oriented. The well-saturated ferroelectric hysteresis loops and the fatigue properties were obtained by hysteresis measurements using a metal-ferroelectric-metal structure. The remnant polarization (2Pr) and coercive field (2Ec) reached to 24.0μC/cm2 and 137.8kV/cm, respectcively in the electric field of 275kV/cm. No fatigue was observed up to 4.4×1010 switching cycles.
The correction of short-range Mie scattering laser lidar returns based on the Gaussian character of laser beam
Authors: Wang Zhi-Hua  , He Ying-Hong  , Zuo Hao-Yi  , Andrew Yuk Sun Cheng  , Yang Jing-Guo  ,   (1)四川大学物理系,成都  610064; (2)香港城市大学物理及材料科学系，香港;四川大学物理系,成都  610064; (3)中国科学院西安光学精密机械研究所，西安  710068;四川大学物理系,成都  610064
Published: December 2020

A new method for correcting Mie scattering laser lidar short-range returns by virtue of Gaussian emission was described. Firstly, basing on the Gaussian character of laser beam, the lidar returns were corrected. Secondly, on the assumptionof an almost homogenous atmosphere, the corrected logarithmic range-adjusted power curve S(r) was fitted with conic section, then the corresponding influences of overlapping area were corrected. Some examples show that the corrected results are much closer to the real atmospheric conditions.
Bi-material mircocantilever array room-temperature IR imaging
Authors: Miao Zheng-Yu  , Zhang Qing-Chuan  , Chen Da-Peng  , Wu Xiao-Ping  , Li Chao-Bo  , Guo Zhe-Ying  , Dong Feng-Liang  , Xiong Zhi-Ming  ,   (1)中国科学技术大学，中国科学院材料力学行为和设计重点实验室，合肥  230027; (2)中国科学院微电子研究所，北京  100029
Published: December 2020

The uncooled IR thermal imaging technology with its wide applications in military, medical and industrial areas has been an active topic in international research. Thermal imaging based on optical readout bi-material microcantilever array is a new concept in methodology. In this paper, a new kind of bi-material micro-cantilever unit with multi-fold legs and interval gild structure is designed and its thermal and thermo-mechanical performance are analylized. A 100×100 microcantilever array is fabricated as a FPA (focal plane array), and by using this FPA, a thermal image of a room-temperature body (human body) is successfully detected. The NETD (noise-equivalent temperature difference) is about 200mK.The experimental results are well accordant with the thermal analysis of the microcantilever unit.
Perturbation of symmetries and Hojman adiabatic invariants for Lagrangian system
Authors: Zhang Yi  , Fan Cun-Xin  , Mei Feng-Xiang  ,   (1)北京理工大学 力学系，北京  100081; (2)苏州科技学院土木工程系，苏州  215011
Published: December 2020

The perturbation of symmetries and adiabatic invariants for Lagrangian system are studied. The exact invariants introduced by the Lie symmetries of Lagrangian system without perturbation are given. Based on the definition of high-order adiabatic invariants of a mechanical system, the perturbation of Lie symmetries for Lagrangian system with the action of small disturbance is investigated, and a type of Hojman adiabatic invariants of the system are obtained. An example is given to illustrate the application of the results.
Modulation and demodulation for detecting weak periodic signal of stochastic resonance
Authors: Lin Min  , Huang Yong-Mei  ,   中国计量学院计量技术工程学院，杭州  310018
Published: December 2020

Modulated stochastic resonance method which can detect weak periodic signals under strong noise in wide parameter conditions is proposed in this paper. The high frequency weak signal mixed with noise is modulated to a low frequency difference signal. The signal conforms to the adiabatic elimination theory. So when it acts on stochastic resonance system, the stochastic resonance can arise. If the low frequency signal is demodulated, the original high frequency weak signal mixed with noise can be relrieved. To deal with the unknown frequency mixed with noise, the frequency of modulate oscillator is changed continuously to achieve a suitable difference frequency signal for inputting to stochastic resonance system. According to the change of resonance spectral peak value, the unknown frequency can be found from the demodulated signal. The method is effective for future application.
On the characteristics of phase transition in CA traffic models
Authors: Guo Si-Ling  , Wei Yan-Fang  , Xue Yu  ,   (1)广西大学物理科学与工程技术学院，南宁  530004; (2)广西大学物理科学与工程技术学院，南宁  530004；广西玉林师范学院物理与信息科学系，玉林  537000; (3)广西大学物理科学与工程技术学院，南宁  530004；上海大学上海市应用数学与力学研究所，上海  200072
Published: December 2020

In this paper, the correlation functions in the CA (cellular automaton) traffic models incorporating the `slow-to-start' rule, such as VDR model, BJH model and T2 model, are systematically studied at different traffic densities. The results show that there are anti-correlations and correlations between cars at low density. When anti-correlation disappears with the increases of density, it means the transition from free flow to jamming. In order to study the characteristics of phase transition, we study the order parameters of these models with the delay probability and slow-to-start probability. We found that the CA traffic model with ‘slow-to-start’ rule will change the characteristics of phase transition. Independently of the delay probability and in the case of less than maximal velocity, the transition from free flow to jamming in the CA model with slow-to-start probability not exceeding 0.5 is the second phase transition, which has an analogy to one in the deterministic NaSch model. Otherwise, the first phase transition will appear. Under conditions of stochastic delay, the crossover phenomena will occur. When the limiting velocity has larger values, it will show the first phase transition in spite of the delay probability.
Numerical study of dynamic effects and evaporation of target material under irradiation of intense pulsed ion beam
Authors: Wu Di  , Gong Ye  , Liu Jin-Yuan  , Wang Xiao-Gang  , Liu Yue  , Ma Teng-Cai  ,   大连理工大学三束材料改性国家重点实验室，大连  116024
Published: December 2020

Gaussian distribution models of voltage wave form of MID of TEMP Ⅱ accelerator and IPIB density near the MID focus region have been built according to the results of experiments. The energy deposited in the target were calculated by using Monte Carlo method based on these models. Then we use them as thermal sources in hydrodynamic equations, and simulate the evolution process of pressure transported in target based on different kinds of state equations of material. The pressure evolution profile of plasma generated by IPIB irradiated Al target with high enough beam energy density has also been calculated by combining the ideal gas model of plasma and HD equations.
Preparation and mechanism of p-type ZnO films formed by modified ion beam enhanced deposition method
Authors: Yuan Ning-Yi  , Li Jin-Hua  , Fan Li-Ning  , Wang Xiu-Qin  , Xie Jian-Sheng  ,   江苏工业学院功能材料实验室，常州  213016
Published: December 2020

In-N codoped ZnO films were prepared on Si and SiO2/Si substrates by modified ion beam enhanced deposition method. ZnO mixed with 2 atm % In2O3 powder was used as sputtering target and during the deposition N+/Ar+ mixed beam was implanted into the deposited films. The XRD results showed that all polycrystalline In-N codoped ZnO films deposited on Si and SiO2 substrates have a preferred (002) orientation and showed p-type conduction. The as-deposited films were annealed in N2 and O2. After annealed in N2 the lowest resistivity of p-type In-N codoped ZnO films was 0.9Ωcm. The dependence of film structure and electrical properties on deposition and annealing condition were discussed.
Current slump mechanism and its physical model of AlGaN/GaN HEMTs under DC bias
Authors: Hao Yue  , Han Xin-Wei  , Zhang Jin-Cheng  , Zhang Jin-Feng  ,   西安电子科技大学微电子学院，西安  710071;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

As the most remarkable effect in GaN microwave power device, Current slump has been studied widely.However,there still exist unsolved proplems.Based on the analysis of experiment and theory on the AlGaN/GaN high electron mobility transistor (HEMT) under dc sweep,an analytical model for the current collapse is developed considering the effects of polarization and surface states.The comparison between simulations and physical measurements shows a good agreement.
Dielectric properties of a three-phase Fe-Ni-BaTiO3 composite
Authors: Huang Ji-Quan  , Hong Lan-Xiu  , Han Gao-Rong  , Weng Wen-Jian  , Du Pi-Yi  ,   (1)浙江大学电气工程学院,杭州  310027; (2)浙江大学硅材料国家重点实验室,杭州  310027
Published: December 2020

Fe-Ni-BaTiO3 three-phase composites with super high dielectric constant were successfully prepared by sintering BaTiO3 with various amount of metal (Ni and Fe with a fixed mol ratio of 78∶22) in nitrogen atmosphere at 1250℃ for 2h. The impedance and the dielectric properties were measured by an Agilent 4294A precision impedance analyzer, and the dc conductivity was measured by a Keithley 6571 high resistance meter. The results indicate that this type of composite undergoes an insulator-conductor transition with increasing metal concentration and the dielectric constant diverged near the percolation threshold. The dielectric constant reaches as high as 22000 when fMetal=0.23, which is about 12 times that of the BaTiO3 matrix, while the dielectric loss keeps still a low and stable value of about 0.08 with increasing metal concentration. And the dielectric relaxation shows a notable Maxwell-Wagner characterization, which suggests that conduction mechanisms may play an important role in the dielectric response.
Theory and calculation of giant magneto-impedance effect in amorphous alloy ribbons and films
Authors: Bao Bing-Hao  , Song Xue-Feng  , Ren Nai-Fei  , Li Chang-Sheng  ,   (1)江苏大学机械工程学院,镇江  212013; (2)江苏大学微纳米科学技术研究中心,镇江  212013;江苏大学材料科学与工程学院,镇江  212013; (3)江苏大学微纳米科学技术研究中心,镇江  212013;江苏大学机械工程学院,镇江  212013
Published: December 2020

The detailed expressions of orientation-related relative permeability in amorphous alloy ribbons and films with in-plane nearly transverse uniaxial anisotropy under applied driving ac current flowing through the ferromagnetic materials and dc external magnetic field are derived by simultaneously solving the Maxwell's equations and the Landau-Lifshitz equation of motion and establishing the magnetic domain structure model. The calculation formula of mean relative permeability averaging over 90°orientation angle and the magneto-impedance are obtained. The relation between permeability and the component of tensor susceptibility is deduced. The dependences of the real part and imaginary part of the relative permeability on frequency at several values of the applied external field are calculated, and the corresponding magnetic permeability spectra are plotted. The calculation formula of permeability which were inferred by Panina et al and Kraus can be unified by our theoretical result which is in good agreement with the experimental data under lower external magnetic field for both amorphous ribbons and films.
Double Jacobian elliptic function expansion method under a general function transform and its applications
Authors: Wu Guo-Jiang  , Han Jia-Hua  , Shi Liang-Ma  , Zhang Miao  ,   安徽大学物理与材料科学学院,合肥  230039
Published: December 2020

A modified double Jacobian elliptic function expansion method under a general function transform, which is more general than the Jacobian elliptic function expansion method under a travelling wave transform, is proposed to construct the exact solutions of nonlinear evolution equations. Some new exact periodic solutions are obtained by this method which include previous solutions, replenishing the known results of the equations.
Characteristic functions and quasi-probability distribution functions of multi-mode Bose quadratic polynomial system
Authors: Xu Xiu-Wei  , Ren Ting-Qi  , Chi Yong-Jiang  , Zhu You-Liang  , Liu Shu-Yan  ,   烟台师范学院物理系，烟台  264025
Published: December 2020

The multi-mode Bose quadratic polynomial system (MBQPS) is studied. The normal, anti-normal, Wigner characteristic functions, P-representation and Q-representation of MBQPS are presented by utilizing the general theory of linear quantum transformation of multi-mode Bose system. And as a example, its quantum squeezed characteristics are studied.
Synchronization of a class of uncertain chaotic systems by observer
Authors: Chen Jing  , Zhang Tian-Ping  ,   扬州大学信息工程学院，扬州  225009
Published: December 2020

This paper investigates the synchronization of a class of uncertain chaotic systems based on reduced-order observer. Without any prerequisite on the nature of the perturbation, a reduced-order observer-based response system is designed for synchronization with the drive system. Numerical simulation shows the effectiveness of the proposed method.
Impact of Gaussian white noise on a two-dimensional neural map
Authors: Song Yang  , Zhao Tong-Jun  , Liu Jin-Wei  , Wang Xiang-Qun  , Zhan Yong  ,   河北工业大学理学院，天津  300130
Published: December 2020

Based on the two-dimensional neural map, we use the Gaussian white noise to imitate the noisy environments of neurons. We investigate the impacts of Gaussian white noise on the phase diagram of parameters. It is found that adding the noise leads to an enhancement of excitability of the system. We also study the coherence resonance (CR) by numerical simulation, and the parameter condition of the CR phenomenon is discussed. Only when the parameters of the system are chosen in the regime of silence and near the dividing line between spiking and silence can we get the CR phenomenon.
Growing complex network model with acceleratingly increasing number of nodes
Authors: Li Ji  , Wang Bing-Hong  , Jiang Pin-Qun  , Zhou Tao  , Wang Wen-Xu  ,   (1)中国科学技术大学近代物理系，非线性科学中心,合肥  230026; (2)中国科学技术大学近代物理系，非线性科学中心,合肥  230026;阜阳师范学院物理系,阜阳  236041; (3)中国科学技术大学近代物理系，非线性科学中心,合肥  230026;广西师范大学物理与信息工程学院,桂林  541004
Published: December 2020

Inspired by the observation that some real-life networks' sizes grow as a geometric series, a growing complex network model with acceleratingly increasing number of nodes is proposed. At each time step, the number of newly added nodes is proportional to the size of the network. This network shows scale-free property when the growing rate r is not large, and its power-law exponent is tunable from 2 to 3 through r. The average path length decreases and clustering coefficient increases with r respectively. In addition, we also give an analytical solution about power-law exponent versus r that agrees well with the simulation result.
Investigation of high order harmonic generation and ionization of model hydrogen atoms and real hydrogen atom in intense laser field
Authors: Zhao Song-Feng  , Zhou Xiao-Xin  , Jin Cheng  ,   (1)西北师范大学物理与电子工程学院,兰州  730070; (2)西北师范大学物理与电子工程学院,兰州  730070;兰州重离子加速器国家实验室,兰州  730000
Published: December 2020

Solving time-dependent Schrdinger equation numerically, we investigate the high-order harmonic generation and ionization probability of one-dimensional, two-dimensional and three-dimensional hydrogen atom exposed to intense laser field. Our results show that high-order harmonic generations and the ionization probabilities of the model atoms and real hydrogen atom are similar both in the multi-photon ionization regime and in the over-barrier ionization regime; in the tunneling ionization regime, the plateau feature and cut-off position of high order harmonic generations of the model atoms and real hydrogen atom are almost the same, and the trend of change of the ionization probabilities with time is similar, but the values of ionization probabilities for the model atoms are different from those for real hydrogen atom. We discuss the reason for the difference of ionization probabilities between the model atoms and the real hydrogen atom according to the classical three-step model.
Elastic properties of single-wall nanotubes
Authors: Zhang Li-Yun  , Peng Yong-Jin  , 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

We report the Young's modulus of a series single-wall carbon nanotubes(armchair type and zigzag type)and BN zigzag type nanotubes on the basis of ab initio theory. According to the calculations, the relation between Young's modulus and the diameter of nanotubes is presented. We have also discussed how the strain energy of rolling effect of all kinds of nanotubes and how the balance basis set a of nanotubes varies with the type of nanotubes.
The internal friction related to dislocation peak in a graphite particulate CuAlMn shape memory alloy composite
Authors: Sun Wei  , Wang Qing-Zhou  , Han Fu-Sheng  ,   (1)浙江工贸职业技术学院，温州  325003; (2)中国科学院固体物理研究所，合肥  230031
Published: December 2020

A composite was fabricated by an infiltration process using graphite particulates for damping enhancement phase and a Cu-11.9Al-2.5Mn (wt%) shape memory alloy as the matrix, and the internal friction of the resulting composite was studied. Two internal friction peaks were observed in the quenched specimens during heating at 240℃ and 370℃ respectively, of which only the evolvement and the mechanism of the low-temperature peak were investigated in the present study. It was found that, the peak only appears in the composite; the location of the peak is independent of frequency but its height increases with increasing frequency; the peak rises and shifts towards high temperature as the heating rate is increased; the height increases with increasing volume fraction of the graphite particulates; and it disappears after several thermal cycles. It is demonstrated from these features together with microstructure examinations that the peak results from the interaction between the applied stress and the dislocations in the matrix.
Nanoelectronic logic circuits with carbon nanotube transistors
Authors: Li Ping-Jian  , Zhang Wen-Jing  , Zhang Qi-Feng  , Wu Jin-Lei  ,   北京大学电子学系,北京   100871
Published: December 2020

We demonstrate logic circuits with carbon nanotube field-effect transistors (CNTFETs). The p-type CNTFETs are fabricated based on single-walled carbon nanotubes and n-type CNTFETs are fabricated based on nitrogen-doped multiwalled carbon nanotubes. To be specitic, we demonstrate three types of logic circuits with CNTFETs, which include an inverter (a p-type CNTFET), a complementary inverter (a p-type CNTFET and an n-type CNTFET in a single clip), and a logic NOR (two p-type CNTFETs).
Magnetic and electronic transport properties of SrTiO3-doped La-K-Mn-O system
Authors: Wu Jian  , Zhang Shi-Yuan  ,   (1)河海大学理学院,南京  210098; (2)南京大学物理系,南京  210093
Published: December 2020

La0.833K0.167MnO3 (LKMO) and La0.833K0.167MnO3/SrTiO3 (LKMO/STO) are fabricated at different temperatures. STLK08, STLK10 and STLK12 stand for the samples sintered at 800, 1000 and 1200℃ respectively. X-ray diffraction (XRD) shows that all of the three samples consisted of homogeneous solid solution phases. The resistivity for LKMO shows insulator-metal transition with decreasing temperature, but the resistivities of STLK10 and STLK12 show an insulator behavior over the whole temperature regime (4—300 K). The low-field (0.02 T) magnetoresistance increases from 0.2% to 11% with temperature decreases from 250 K to 4 K for STLK12 sample. The high field (μ0H=5.5 T) magnetoresistance almost increases linearly with decreasing temperature, which is much higher than the magnetoresistance of LKMO (The high field magnetoresistance are 65% and 40% at 4 K for STLK12 and LKMO, respectively). The enhancement in magnetoresistance is quantitatively explained by spin-polarized-tunneling at grain boundaries.
Effect of O2-doping on bonding configuration and electric properties of SiCOH films prepared by decamethylcyclopentasiloxane electron cyclotron resonance plasma
Authors: Wei Yong-Xia  , Qian Xiao-Mei  , Yu Xiao-Zhu  , Ye Chao  , Ning Zhao-Yuan  , Liang Rong-Qing  ,   (1)复旦大学现代物理研究所，上海  200433; (2)苏州大学物理科学与技术学院，江苏省薄膜材料实验室，苏州  215006
Published: December 2020

Carbon-doping oxide materials (SiCOH films) with k of 2.62 are prepared by electron cyclotron resonance chemical vapor deposition (ECR-CVD) from the mixture of decamethylcyclopentasioxane (D5) and oxygen (O2). This paper investigates the effect of O2-doping on bonding configuration, dielectric property and leakage current of the SiCOH low dielectric constant films. The results show that the leakage current can be reduced obviously on the premise that dielectric constant k is kept at a lower value by small O2-doping amount. For the SiCOH film deposited under O2 flow of 3 cm3/min, the dielectric constant k as low as 2.62 and leakage current of 8.2×10-9 A/cm2 can be obtained.
Large optical nonlinearities in Ag-doped BaTiO3 nanocomposite films
Authors: Yang Guang  , Chen Zheng-Hao  ,   (1)武汉光电国家实验室激光科学与技术研究部,华中科技大学,武汉  430074；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
Published: December 2020

Ag-doped BaTiO3 nanocomposite films have been synthesized on MgO substrates by excimer laser deposition. X-ray diffraction was used to characterize the structure and crystallinity of the films. The Ag chemical band and concentrations in the composite films were determined by X-ray photoelectron spectroscopy. The optical absorption were measured in the range of 300 to 800 nm and the absorption peaks due to the surface plasmon resonance of Ag particles were observed. z-scan results showed that the films exhibited large optical nonlinearities and the signs of the nonlinear absorption, β, and nonlinear refractive index, n2, changed with the increase of Ag concentration. The mechanism of the enhanced optical nonlinearities in Ag: BaTiO3 films is discussed.