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August 15,2008
Volume 1,Issue 7
Pages 724-843
Subject Area:Condensed Matter Physics,Applied Optics,High-energy Physics,Condensed State Theory,Electromagnetic Wave Physics,Crystallology(Crystal Growth,Crystal Chemistry),Atom Molecule Physics

Title: Grain size effect of electical conductivity and giant magnetoresistance effect in bulk magnetic polycrystals

Authors: LUO Wei, ZHU Linli, ZHENG Xiaojing
PP: 786～792
Abstract: Solving Boltzmann equation and considering the spin-dependent grain boundary scattering, the distribution of electrons in grains and the electrical transport properties in applied magnetic field are discussed. Considering the dominate influence of grain boundary scattering, taken as boundary conditions for electrical transport, investigated the dependence of electrical conductivity on grain size. Simultaneously, in applied magnetic field, the reoritention of the relative magnetisation between grains brings the change of spin, and it presents obvious giant magnetoresistance (GMR) effect. The results indicate that as the grain size decreases, the electrical conductivity descends evidently, and when the grain size is much smaller, the GMR effect is more obvious.
Keywords: condensed matter physics; electrical conductivity; spin; the mean free path of electron; magnetisation; giant magnetoresistance (GMR) effect; grain size

Title: Analysis of step-index plastic optical fiber bending loss

Authors: KONG Xiangze, LI Wei
PP: 838～843
Abstract: This paper analyses the bending loss of step-index plastic optical fiber(POF) using geometric approach. The radiation loss only occurs at reflection points, and can be described by the power-transmission coefficient T which is different for tunnelling and refracting rays. A numerical simulation shows that the bending loss of step-index POF becomes larger as the curve radius is less than 20 mm. This result is helpful to design a mode scrambler which is used in step-index POF measurements.
Keywords: optical; plastic optical fiber bending loss; step-index; tunnelling ray; power-transmission coefficient; mode scrambler

Title: Study of energy coupling in resonant tunneling process

Authors: JIA Guozhi，YAO Jianghong
PP: 834～837
Abstract: A Schr錸dinger equation has been solved numerically for a barrier in a quantum well by the transfer matrix technique to analyze resonant tunneling process of electronics theoretically. Effects of the middle barrier on energy coupling between quantum wells were investigated. The result of analysis showed that the key factor affect the transmission intensity and energy was the thickness of the middle barrier and the width of the second quantum well. Effect of structure parameters on the transmission probabilities were investigated in detail. The results suggested that the symmetry should play an important role in coupling effect between the quantum wells. The resonant energy peak with 1.9 eV kept being constant, which can correspond with the ground state energy level of the first quantum well. The other transmission peak varied with the increase of width of the second quantum well. When the widths of the two wells were the same, the transmission probability was the maximum.
Keywords: low dimensional physics; resonant tunneling; energy couple; transfer matrix

Title: Production of the new particles predicted by the LHT model at high energy collider

Authors: LIU Jinyan, YUE Chongxing, WEN Jia
PP: 827～833
Abstract: Little Higgs theory is proposed as an interesting solution to the so called hierarchy problem of the standard model (SM) and can be regarded as one of the important candidates for new physics beyond the SM. The littlest Higgs (LH) model is one of the simplest and phenomenological viable models, which has all essential features. However, the LH model has the fine-tuning problem. To alleviate this difficulty, a Z2 discrete symmetry, named “T parity”, is introduced into the LH model, which forms the so-called LHT model. The LHT model predicts the existence of the new particles, such as new gauge bosons, T-odd fermions, and scalars. This paper considers the production of these new particles in future high energy collider experiments. The numerical results show that, in wide range of the parameter space, some of these new particles can generate observable signals in future high energy collider experiments. The results will help to test the Little Higgs theory and further to detect new particles at present and in future high energy collider experiments.
Keywords: high energy physics; the LHT model; production cross section; new particle

Title: Vacuum fluctuations based view of the motion of particles in gravitational space

Authors: YE Xinghao
PP: 816～826
Abstract: To reach a deep understanding of the gravitational interaction, this paper investigates the motion of photons and other particles in gravitational field. The study is based on the vacuum fluctuational model of gravitational space. Both the effect of special relativity and the effect of vacuum refraction are considered. The result is just the same as that given by general relativity, though no use of the concept of curved spacetime. Further investigation indicates that, the two types of motion can be simply unified into a wave motion if an integrated refractive index of vacuum is adopted.
Keywords: theory of gravitation; vacuum fluctuation; vacuum refraction; motion of particles; special relativity; general relativity

Title: Influence on the orbital angular momentum spectrum caused by the misalignment of detection system

Authors: LIU Yidong, GAO Chunqing, QI Xiaoqing
PP: 810～815
Abstract: When the orbital angular momentum of light beam is used in the free space optical communication, the misalignments of the detection system, i.e. lateral shift and angular tilt, will diffuse the orbital angular momentum spectrum and therefore cause the wrong orbital angular momentum states and error emergence. To deal with this problem, the affections on the orbital angular momentum spectrum of the misalignments should be clarified. In this work, a quantum operator method is used to analyse the influence on the orbital angular momentum spectrum caused by the misalignments of the detection system in free space optical communication, and the calculation is also given to directly show the mechanism of the affections. This work also gives clear physical meaning and simple mathematical expression of these two kinds of affections and the results show similar influence caused by the two kinds of misalignment which obey the rule denoted by the first kind Bessel function. The work is important in the correction of the orbital angular momentum spectrum in free space optical communication by using the orbital angular momentum.
Keywords: physical electronics; orbital angular momentum; orbital angular momentum spectrum; free space optical communication

Title: Monte Carlo simulation of 3-D Ising model

Authors: WU Yang, DUAN Haiming
PP: 805～809
Abstract: In this article, 3-D Ising model is simulated by the means of Monte Carlo, such as the simple cubic lattice, the body-centered cubic lattice and the face-centered cubic lattice. It is a computer simulation method, using random sampling, to compare realistic description of the real physics experiment with good accuracy, and draw analysis of the three critical state and other physical changes in nature by programming data. The result suggests that under high temperature, the magnetic of the systems disappears, and at low temperature, it is magnetic, with a transition. The paper also studied the susceptibility, energy and heat capacity as a function of the temperature of the three lattice models. The three-dimensional Ising model is contrasted with abroad results, and it is entirely consistent with the margin of error.
Keywords: condensed matter physics; three-dimensional Ising model; Monte Carlo method; transition

Title: Study of the g-factor in electron paramagnetic resonance

Authors: LI Zebin, NIU Yingxi, WEI Xuesong, LV Haiping, YIN Chunhao
PP: 800～804
Abstract: g-factor is able to be measured by EPR. It is to know the local magnetic field trait of internal configuration of molecule, and also to judge how much the spin angle momentum and the orbit angle momentum contribute to the electron magnetic moment. Therefore, the measurement of g-factor is one of important aspects of knowing paramagnetic matter trait. So, it is to get Land g-factor from the theory, and to study the reasons why g-factor value deviates from ge in the different situation. In this foundation, a couple of methods to measure g-factor are given.
Keywords: condensed matter physics; electron paramagnetic resonance; g-factor; demarcation method; angular momenta

Title: The analysis of vector field for the Grüner sequation and charge-density waves

Authors: LI Liangang, RUAN Yongfeng
PP: 793～799
Abstract: The Grüner s equation is a classical model for studying the charge-density wave, which is a typical nonlinear differential equation. Although GR媲NER proposed the equation, it hadn t been solven rigorously. This paper analyzes the equation by the method of the rotating vector field theory. Using the mathematical analysis obtains the relation between the applied field E and the periodical solution of the equation, and the conclusion that in the over damping situation the E0 in Grüner s equation is just the critical value of the applied field E. The theoretical formulae derived from those, for describing nonlinear conductivity of charge density wave, is consistent with the experiential formula given by FLEMING.
Keywords: condensed matter physics; chargedensity wave(CDW); pendulum; nonlinear conductivity; Grüner s equation; rotating vector field

Title: Transport properties of Nd0.75Sr1.25CoO4 thin films

Authors: HUANG Shengli, RUAN Keqing, LV Zhangming, WU Huiyan, LIN Chunhua, CAO Liezhao
PP: 779～785
Abstract: Single crystal thin films Nd0.75Sr1.25CoO4 were grown on the (100)-LaAlO3 (LAO) and (100)-LaSrAlO4 (LSAO) substrates. Temperature dependence of the electrical resistance (ρ) and thermoelectric power(S) were investigated in the ab-plane. In the whole temperature region measured (70 K Keywords: condensed matter physics; thermally activated mode; variable range hopping(VRH) mode; Zvyagain formula; energy gap

Title: Analysis of one-dimensional photonic crystal planar waveguide

Authors: WANG Zhongzhu, WU Xianliang,SHA Wei
PP: 773～778
Abstract: One-dimensional photonic crystal planar waveguide is presented as sandwich structure of a dielectric planar guide stacked by one-dimensional photonic crystals consisting of a periodic multilayer planars. Transfer matrix method (TMM) is used to analyze stop band property of one-dimensional photonic crystals at the normal incidence for electromagnetic wave, its first stop band lies in the range of 73～99 THz, the center frequency is 86.3 THz. Additionally, transmission properties of one-dimensional photonic crystal planar waveguide in the range of fivst stop band is investigated based on multilayer dielectric planar waveguide analysis method. The results show that only TE and TM main modes can propagate in waveguide, furthermore, power constrained factor (Γ) of TE main mode is in 0.99～1, in other words, electromagnetic wave is fully constrained in dielectric planar guide, which is coined with the prediction property of photonic crystals.
Keywords: electromagnetic field and microwave; photonic crystal planar waveguide; photonic band-gap; guidance mode; power constrained factor

Title: Statistical characteristics of the exponential refractivity profiles under atmospheric duct environment

Authors: LIU Chengguo, WANG Yuan, WU Xunying
PP: 767～772
Abstract: The characteristics of exponential atmospheric refractivity profile under atmospheric duct are investigated with air refractivity at height of 1 km and the average gradient of refractivity 1 km above ground as the characteristic parameters, their correlation with surface refractivity included also. The methods of modeling and statistic are elaborated; the results depicted in detail are applicable. Based on the data of 5 years in 1970s with duct present and those of December 1990, refractivity at height of 1 km, the average gradient of refractivity and surface refractivity are obtained by regression of the refractivity profiles to exponential models. And it is found that the constants in the exponential relation of refractivity of 1 km above ground and the mean vertical refractivity gradient in the first kilometer height with the surface value of refractivity are 110.6, 0.002 9 and -8.6, 0.004 7 respectively according the data of the 1970s\' surface ducts, and the correlations under duct environment are better than under other environment.
Keywords: radio physics; radio meteorology; atmospheric refractivity; atmospheric duct; radio wave propagation

Title: Direct lattice vector and reciprocal lattice vector in curvilinear coordinate systems

Authors: WANG Hongji
PP: 763～766
Abstract: In solid physics, using direct lattice vector and reciprocal lattice vector to describe the physical characters of crystal structure. Direct lattice vector and reciprocal lattice vector are all invariant of magnitude and direction constant vectors. Quasi-crystal, liquid crystal, ferromagnetic material, polymer, and so on, have local structure and dynamic structure, cannot be described by direct lattice vector and reciprocal lattice vector. For describing this local structure and dynamic structure, this paper extends the concept of direct lattice vector and reciprocal lattice vector to general curvilinear coordinate system, obtains direct lattice vector and reciprocal lattice vector in general curvilinear coordinate systems.
Keywords: crystallology; crystal structure; direct lattice vector; reciprocal lattice vector

Title: Analysis of the polarization characteristic of optic ring resonator

Authors: WANG Shijun, MA Huilian, JIN Zhonghe
PP: 759～762
Abstract: The resonator optic gyro(ROG) is a novel inertial rotation sensor, which uses resonance frequency change due to the Sagnac effect to measure for rotating sensing. Through research on the noise sources in the ROG, the polarization fluctuation in ring resonator has shown to be one of the dominant noise sources. This paper analyzes the polarization characteristic of light propagation in ROG. A universal model is set up, which can analyze resonance curve of polarization characteristic in ring resonator. The polarization fluctuation based on the basic element parameters of the ROG can be obtained using this model. It also presents how to select a ring resonator for the smallest polarization fluctuation of the ROG.
Keywords: optics; optical sensors; ring resonator; Jones matrix; polarization

Title: Investigation into anomeric effect of dimethoxymethane in momentum space

Authors: HUANG Yanru, NING Chuangang, ZHANG Shufeng, LIU Kun, LUO Zhihong, Deng Jingkang
PP: 753～758
Abstract: Anomeric effect of G+G+ conformer of dimethoxymethane was firstly investigated in momentum space using the improved 3rd generation electron momentum spectrometer. The experimental data and theoretical results obtained from HF, DFT/B3LYP and ADC(3) calculations for its G+G+ conformation display that along C-O-C-O-C backbone through-orbital and through-space electronic interactions caused by anomeric effect localizes orbital 10a, That is to say, its ionization energy is higher about 1.6 eV than one of close orbital 9b, corresponding it is observed that there is a wide gap between two peaks relative with these orbitals from HeI photoelectron spectroscopy. A comparison of DFT calculations upon spherically averaged (e, 2e) electron momentum distributions with 1p-GF/ADC(3) ones shows that it is essential that inclusion of diffuse functions in employed various basis sets to correctly describe the experimental results for momentum profile and enables us to identify specific fingerprints of through-space orbital interactions associated with the anomeric effect.
Keywords: electron momentum spectroscopy; anomeric effect; 1p-GF/ADC(3); dimethoxymethane

Title: Partially incoherent accessible solitons in strongly nonlocal media

Authors: KONG Qian, SHI Jielong, SHEN Ming, WANG Qi
PP: 745～752
Abstract: This paper studies the propagation of incoherent accessible solitons in strongly nonlocal media with arbitrary response function. Based on the linear propagation equation and the mutual coherence function approach, an exact analytical solution of such incoherent accessible solitons is obtained. The solitons radius is related to the total power as well as the coherence characteristics of the incoherent beam. The result shows that there is not a threshold for incoherent solitons exist in strongly nonlocal media because the model is linear. Evolution behaviors of the solitons width and the coherence radius are also described when the solitons undergo linear harmonic oscillation.
Keywords: radio physics; incoherent solitons; strongly nonlocal media; mutual coherence function approach

Title: Microstructure and microwave absorbing properties of PANI/ferrite composite materials

Authors: LI Mao, FANG Qingqing, WANG Weina, XIONG Weihua,ZHOU Jun, WANG Shengnan, YAN Qingsheng
PP: 740～744
Abstract: PANI/ferrite composite particles were prepared by in-situ composite method. Transmission electron microscope(TEM), X-ray diffraction(XRD) and Fourier transform infrared spectrometer（FT-IR） were used to observe and measure the morphology, microstructure and properties. The absorption properties were measured using a vector network analyzer in frequency rang of 0.5～20 GHz. The experiment results showed that the composites materials with core/shell structure exhibits excellent microwave absorbing properties. When 15wt% Li0.45Zn0.1Fe2.45O4 was incorporated into PANI, the microware absorbing properties of composite particles were the best. The peak value of absorption quantities was 26.1 dB and -8 dB bandwidth reached 5 GHz, and the area density was the least 0.28 g/cm2.
Keywords: materials science; absorbing materials; PANI/ferrite; absorbing properties; core/shell structure

Title: Alignment of diatomic molecule in a nonresonant femtosecond laser field

Authors: LIU Fuchun, JIN Mingxing, LU Xiuxiu, DING Dajun
PP: 735～739
Abstract: A study on alignment of linear diatomic molecules in their electronic ground state is given based on a theoretical description of molecule-laser interaction through time-dependent Schr錸dinger equation. This method is applied to numerically simulate, by four order Runge-Kutta method, the alignment of diatomic molecule ICl in a nonresonant ultrashort laser field within the intensity of I=1010～1013 W/cm2. The results show that, after interacting with the femtosecond laser, a coherent superstition of field-free molecular rotational states occurs and the alignment of molecules is periodically reconstructed.
Keywords: atomic and molecular physics; molecular alignment; femtosecond laser; diatomic molecule; numerical calculation

Title: Thickness dependent microstructure of La0.9Sr0.1MnO3/ Si films

Authors: HUANG Chunkui, SU Qing, XU Jinhai, LAN Wei, LIU Xueqin
PP: 729～734
Abstract: La0.9Sr0.1MnO3 film on Si(100) substrate with a variety of thickness was prepared by sol-gel routine, and the microstructure of LSMO/Si was studied by XRD and confocal micro Raman spectroscopy technology. Both XRD and Raman results show different structure of LSMO film with different thickness. There are two strong peaks around 490 cm-1 and 602 cm-1 that is characteristic of Jahn-Teller distortion in spectra and characteristic peak of rhombohedral structure of the film with thickness of 90 nm that show coexistence of two phases. Lattice constants of LSMO film vary with film thickness. Lattice constants vary as film thickness increased, which is because the tilting angle of MnO6 octahedron and the bond length of Mn-O increase as film thickness increasing. As the results of Raman spectra of 532 nm laser and 325 nm laser show, there are two phase exist in LSMO/Si film, that is orthorhoderal in LSMO/Si interface, but rhombohedral in surface.
Keywords: condensed matter physics; La1-xSrxMnO3; thin film; confocal micro-Raman spectroscopy; microstructure

Title: Preparation and thermoelectric properties of Yb0.15Co4Sb12 based nanocomposites with CoSb3 nano-inclusion

Authors: MI Jianli, ZHAO Xinbing, ZHU Tiejun
PP: 724～728
Abstract: Nanocomposites offer a promising approach to incorporate nanostructured constituents to bulk thermoelectric materials. Bulk skutterudite nanocomposites of Yb0.15Co4Sb12 with different contents of CoSb3 nano-inclusion were prepared by spark plasma sintering. The nanocrystals in the bulk composites are less than 100 nm. The Seebeck coefficient is enhanced by potential barrier scattering with incorporating a small amount of CoSb3 nanoparticles into the bulk materials, but depressed with further increasing content of the nanoparticle. Though the nano-inclusion is the unfilled CoSb3, it is effective in reducing thermal conductivity. The highest figure of merit reaches 0.9 for nanocomposites, about 10% increase compared with the Yb0.15Co4Sb12 matrix.
Keywords: semiconductor physics; thermoelectric properties; solvothermal synthesis; nanocomposite; skutterudite

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