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Volume 30 Issue 12
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GENERAL
Ohmic Losses in Coaxial Cavity Gyrotron with Outer Corrugation
HOU Shen-Yong, YU Sheng, LI Hong-Fu
Chin. Phys. Lett. 2013, 30 (12): 120201 .   DOI: 10.1088/0256-307X/30/12/120201
Abstract   PDF(pc) (642KB) ( 714 )
Ohmic losses of a coaxial cavity gyrotron with outer corrugation are investigated. The results show that the averaged ohmic loss densities of the inner and outer conductors have similar changes along with the axial direction of the gyrotron; whereas averaged ohmic loss densities of the outer conductor are more than the inner conductor; the outer slot depth and width cause greatly the averaged ohmic loss densities of the corrugation bottom and the corrugation period of outer conductor, and averaged densities of ohmic losses on the inner conductor are almost unaffected.
Thermal Entanglement in a Two-Qubit Ising Chain Subjected to Dzyaloshinsky–Moriya Interaction
B. G. Divyamani, Sudha
Chin. Phys. Lett. 2013, 30 (12): 120301 .   DOI: 10.1088/0256-307X/30/12/120301
Abstract   PDF(pc) (479KB) ( 359 )
Thermal entanglement of a two-qubit Ising chain subjected to an external magnetic field and Dzyaloshinsky–Moriya (DM) interaction is examined. The effect of magnetic field, strength of DM interaction and temperature are analyzed by adopting negativity of partial transpose as the measure of entanglement. It is shown that when the DM interaction along the Ising axis is considerable, thermal entanglement can be sustained for a higher temperature. The usefulness of longitudinal DM interaction over the one that is perpendicular to the Ising axis, in the manipulation and control of entanglement at a feasible temperature, is illustrated.
Asymmetric Model of the Quantum Stackelberg Duopoly
WANG Xia, LIU Di, ZHANG Jun-Pei
Chin. Phys. Lett. 2013, 30 (12): 120302 .   DOI: 10.1088/0256-307X/30/12/120302
Abstract   PDF(pc) (2474KB) ( 315 )
A more efficient model of the quantum Stackelberg duopoly is proposed by using the asymmetric quantization scheme of Qin et al. In this model, two entanglement factors α (α=√γ12) and γ (γ=√γ1γ2) are introduced, which greatly expands the functions of the previously reported symmetric one. By choosing proper values of α and γ, one can better manage the market, such as suppressing the first-mover advantage and enhancing the second-mover profit to avoid abuse of oligopolistic competition, and optimizing the total quantity of the products, so to overcome the deficiencies of "first mover always wins" and "positive quantum entanglement always reduces the total quantity" in the symmetric model. The proposed model here is believed to be a good tool for the government and the department to improve the economic efficiency and develop the market.
A Parameter-Space Analysis of the Rikitake System
Rodrigo A. da Silva, Paulo C. Rech
Chin. Phys. Lett. 2013, 30 (12): 120501 .   DOI: 10.1088/0256-307X/30/12/120501
Abstract   PDF(pc) (2067KB) ( 440 )
We investigate analytically and numerically the dynamics of the Rikitake system. The Routh–Hurwitz criterion is used to study the stability of the equilibrium points of the differential equation system model, as functions of two parameters. The dynamics of the model are numerically studied using diagrams that associate colors to the largest Lyapunov exponent value, in two-dimensional parameter spaces. Additionally, phase-space plots and bifurcation diagrams are used to distinguish periodic and chaotic attractors.
THE PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
Holographic Superconductor Models with RF2 Corrections
ZHAO Zi-Xu, PAN Qi-Yuan, JING Ji-Liang
Chin. Phys. Lett. 2013, 30 (12): 121101 .   DOI: 10.1088/0256-307X/30/12/121101
Abstract   PDF(pc) (537KB) ( 259 )
We investigate the effect of the RF2 correction on the holographic superconductor model in the background of AdS black hole, where R is the Ricci scalar of spacetime and F2=FμνFμν is the Maxwell field strength. We observe that, similar to the effect caused by the Weyl correction, the higher RF2 correction term can make it easier for the scalar operator to condense and result in the larger deviation from the expected relation in the gap frequency. However, we find that the condensation gap becomes larger as the RF2 correction term increases, which is in strong contrast to the influences of the Weyl correction and Gauss–Bonnet correction.
NUCLEAR PHYSICS
Description of the Rigid Triaxial Deformation at Low Energy in 76Ge with the Proton-Neutron Interacting Model IBM2
ZHANG Da-Li, DING Bin-Gang
Chin. Phys. Lett. 2013, 30 (12): 122101 .   DOI: 10.1088/0256-307X/30/12/122101
Abstract   PDF(pc) (503KB) ( 341 )
We investigate properties of the low-lying energy states for 76Ge within the framework of the proton-neutron interacting model IBM2, considering the validity of the Z=38 subshell closure 88Sr50 as a doubly magic core. By introducing the quadrupole interactions among like bosons to the IBM2 Hamiltonian, the energy levels for both the ground state and γ bands are reproduced well. Particularly, the doublet structure of the γ band and the energy staggering signature fit the experimental data correctly. The ratios of B(E2) transition strengths for some states of the γ band, and the g factors of the 2+1, 2+2 states are very close to the experimental data. The calculation result indicates that the nucleus exhibiting rigid triaxial deformation in the low-lying states can be described rather well by the IBM2.
Effects of In-Medium Nucleon-Nucleon Cross Section and Nuclear Density Distribution on the Proton-Nucleus Total Reaction Cross Section
HAN Rui, CHEN Zhi-Qiang, R. Wada, ZHANG Su-Ya-La-Tu, LIU Xing-Quan, LIN Wei-Ping, JIN Zeng-Xue, HU Bi-Tao
Chin. Phys. Lett. 2013, 30 (12): 122501 .   DOI: 10.1088/0256-307X/30/12/122501
Abstract   PDF(pc) (656KB) ( 367 )
We present the proton-total reaction cross sections σR by comparing the experimental data with the Glauber model calculation using four sets of nucleon-nucleon cross sections used in literature (free nucleon-nucleon cross sections (NNCS), phenomenological NNCS, Bruckner-type NNCS and Pauli NNCS) and different nuclear densities for symmetric and asymmetric nuclei. For light symmetric target nuclei, the experimental σR data are well reproduced by the former three NNCS with the ground state density distributions of relativistic mean-field theory. On the other hand, for asymmetry heavier target nuclei, the calculations of the σR data depend significantly on the nuclear density distribution at large radius in the low energy region. The experimental σR of these nuclei are well reproduced by the empirical 3 pF density distribution and the in-medium NNCS. The neutron surface distributions are also discussed based on the 3 pF nuclear charge distributions.
ATOMIC AND MOLECULAR PHYSICS
Development of an Integrating Sphere Cold Atom Clock
ZHENG Ben-Chang, CHENG Hua-Dong, MENG Yan-Ling, XIAO Ling, WAN Jin-Yin, LIU Liang
Chin. Phys. Lett. 2013, 30 (12): 123701 .   DOI: 10.1088/0256-307X/30/12/123701
Abstract   PDF(pc) (540KB) ( 348 )
The Ramsey fringes with a linewidth of 45 Hz and a signal-to-noise ratio of 120 are demonstrated for a integrating sphere atom clock. The cycle time of the atom clock is reduced to 80 ms with the help of a pulsed cooling method. This result indicates that the short-term stability of the clock is in the order of 10?12.
A Configurable Surface-Electrode Ion Trap Design for Quantum Information Processing
LIU Wei, CHEN Shu-Ming, CHEN Ping-Xing, WU Wei
Chin. Phys. Lett. 2013, 30 (12): 123702 .   DOI: 10.1088/0256-307X/30/12/123702
Abstract   PDF(pc) (837KB) ( 262 )
We propose a configurable surface-electrode ion trap design to alleviate the poor reusability of the existing traps. It can architecturally and electrically support 5 mainstream modes by design reuse, thus enhancing the trap reusability and reducing the experiment setup overhead. We also develop a corresponding simulation suite which can optimize trap geometries and calculate trap parameters to control the trapped ion's classic motion. According to our analytical and simulated results, the configurable design can serve as a unified platform for basic research of large-scale quantum information processing.
FUNDAMENTAL AREAS OF PHENOMENOLOGY(INCLUDING APPLICATIONS)
Composite Scattering from an Arbitrary Dielectric Target above the Dielectric Rough Surface with FEM/PML
XU Run-Wen, GUO Li-Xin, FAN Tian-Qi
Chin. Phys. Lett. 2013, 30 (12): 124101 .   DOI: 10.1088/0256-307X/30/12/124101
Abstract   PDF(pc) (936KB) ( 367 )
A numerical approach of the finite element method is extended to study the scattering properties of an arbitrary dielectric target above the dielectric rough surface. For scattering in an open region, the artificial boundaries should be introduced to truncate the infinite computational domain. A perfectly matched layer (PML), as the artificial boundary of the finite-element-method (FEM) region, is employed to absorb the outward wave scattered from the model. The strategies of hybrid FEM/PML are presented with their validity evaluated by finite element/boundary integral method (FE/BIM), and then the scattering properties of the dielectric composite problem with different material permittivity are discussed in detail. Compared with the published works about FEM/PML, we extend the FEM/PML into the simulations of a dielectric target above the dielectric rough surface.
Self-Aggregation Enhanced Third-Order Optical Nonlinearities of Aryloxy Substituted Zinc Phthalocyanines
LI Zhong-Yu, WU Chun-Hui, HUANG Xin, XU Song
Chin. Phys. Lett. 2013, 30 (12): 124201 .   DOI: 10.1088/0256-307X/30/12/124201
Abstract   PDF(pc) (813KB) ( 340 )
Third-order optical nonlinearities of three aryloxy substituted phthalocyanines are measured by femtosecond forward degenerate four-wave mixing technique at 800 nm. Ultrafast optical responses are observed and the magnitude of the second-order hyperpolarizabilities γ of the phthalocyanines is measured to be as large as 10?31 esu. Due to the enhancement of J-aggregates, the γ value of an aryloxy substituted zinc phthalocyanine in chloroform is approximately 2.2 times larger than that of the dye in methanol. Moreover, the morphologies of aryloxy substituted zinc phthalocyanine in chloroform exhibit that the nanowires with a diameter of 50–100 nm are connected to each other to form an indefinite network structure, while no aggregates are detected when the samples are prepared from a solution in the methanol.
Real-Time Liquid Evaporation Rate Measurement Based on a Microchip Laser Feedback Interferometer
TAN Yi-Dong, ZHANG Song, REN Zhou, ZHANG Yong-Qin, ZHANG Shu-Lian
Chin. Phys. Lett. 2013, 30 (12): 124202 .   DOI: 10.1088/0256-307X/30/12/124202
Abstract   PDF(pc) (556KB) ( 587 )
We present a novel scheme to realize the direct real-time measurement of liquid evaporation rate and nanometer order liquid level monitoring. It is based on the phase measurement technology of Nd:YAG microchip laser frequency-shifted feedback, which not only has a high resolution and precision but also ultrahigh sensitivity. The evaporation rates of four different transparent liquids and hot water are measured. Experimental results indicate the ease and convenience of measuring and present promising application prospects in non-cooperative target measurement.
Robust Generation of Qutrit-Qutrit Entanglement through a Single Resonant Interaction Assisted by Moderate Driving
WU Huai-Zhi, YANG Zhen-Biao
Chin. Phys. Lett. 2013, 30 (12): 124203 .   DOI: 10.1088/0256-307X/30/12/124203
Abstract   PDF(pc) (802KB) ( 240 )
We propose to engineer qutrit-qutrit entanglement through resonant atom-cavity interaction assisted by moderate laser driving, study two parameter regimes, respectively, of asymmetric atom-laser coupling and of asymmetric atom-cavity coupling, and find that both the coupling regimes possess the advantage of short operation time, compared with the previous ones achieved by dispersive interaction, adiabatic passage, and even quantum Zeno dynamics. We check numerically the influences of the parameter fluctuations and dissipation on the scheme and show it to be robust. The scheme can also be generalized to other physical systems such as the ion trap.
Quantitative Thermoacoustic Tomography for ex vivo Imaging Conductivity of Breast Tissue
HUANG Lin, RONG Jian, YAO Lei, QI Wei-Zhi, WU Dan, XU Jin-Yu, JIANG Hua-Bei
Chin. Phys. Lett. 2013, 30 (12): 124301 .   DOI: 10.1088/0256-307X/30/12/124301
Abstract   PDF(pc) (1146KB) ( 328 )
We assess the feasibility of our developed quantitative thermoacoustic tomography (qTAT) system for breast tumor characterization using mastectomy specimens before the clinical investigation. A circular scanning TAT system coupled with a finite-element based reconstruction algorithm is used to recover the dielectric property distribution of normal and tumor tissues from three female subjects who underwent mastectomy. Statistical method is used to analyze the tissue dielectric properties obtained. The recovered qTAT images reveal large contrast in conductivity between tumor and normal breast tissues. In addition, significant difference in conductivity exists among all the specimens examined. Finally, the recovered tumor size for these specimens agrees well with their exact size. This preclinical evaluation suggests that it is feasible to detect and characterize a breast tumor quantitatively with our qTAT method.
Second-Harmonic Generation of a Plane Wave Normally Incident upon a Solid Plate Immersed in Liquid
DENG Ming-Xi, XIANG Yan-Xun, WANG Ping, LV Xia-Fu
Chin. Phys. Lett. 2013, 30 (12): 124302 .   DOI: 10.1088/0256-307X/30/12/124302
Abstract   PDF(pc) (701KB) ( 293 )
We theoretically investigate the second-harmonic generation of a plane longitudinal wave normally incident upon a solid plate immersed in liquid. The formulation of the reflected second harmonic is derived within the second-order perturbation. Theoretical analysis and numerical simulation indicate that the reflected second-harmonic amplitude increases sensitively with the increase in the nonlinear acoustic parameter of the plate material at some specific frequencies where the linear reflection coefficient of the normally incident longitudinal wave takes on the minimum value, and that it is independent of the spatial separation between the transmitter/receiver and the solid plate. The results obtained provide a means through which the early state of fatigue-induced damage of the solid plate (characterized by its nonlinear acoustic parameter) can be sensitively assessed by measuring the reflected second harmonic at the specific frequency where the linear reflection coefficient is minimum.
Forward Procedure of Magneto-Acousto-Electric Signal in Radially Stratified Medium of Conductivity for Logging Models
GUO Liang, LIU Guo-Qiang, XIA Hui, CHEN Jing
Chin. Phys. Lett. 2013, 30 (12): 124303 .   DOI: 10.1088/0256-307X/30/12/124303
Abstract   PDF(pc) (506KB) ( 302 )
Magneto-acousto-electric tomography (MAET) is known as a method of impedance tomography, with the procedure of acoustic waves propagating in a static magnetic field and producing the electric signal attributing to Lorentz force. We analyze the method of calculating the electric signal with given sound sources and magnetic field in the radially stratified medium of conductivity. It consists of finding an analytic solution of the sound propagating in homogeneous acoustic medium and applying to the data one of the algorithms (the FD method) for the electric scalar potential field. The ideal well logging model is considered in our algorithm, which is very different from the ordinary one in arrangement of the sound sources and electrodes in medical tomography. Combining the analytical and numerical methods in coupled fields for the well logging model is a stable algorithm in forward procedure of MAET.
Nonlinear Acoustic-Optical Effect and Extraordinary Diffraction Distribution in Liquid Surface
MIAO Yang, WANG Shao-Ping
Chin. Phys. Lett. 2013, 30 (12): 124304 .   DOI: 10.1088/0256-307X/30/12/124304
Abstract   PDF(pc) (488KB) ( 321 )
Nonlinear acoustic-optical effect is discovered by using a low-frequency liquid surface acoustic wave with great amplitude. There are higher harmonics in diffracted light and the intensity of the higher harmonic has the relation of Bessel's function with the amplitude. The light patterns diffracted by the wave can be classified into the ordinary and extraordinary beams which are corresponding to small and great amplitudes of the waves. The ordinary and extraordinary patterns are observed experimentally and the critical amplitude value is found.
Experimental Observation of Quasi-Static Avalanche Process of a Granular Pile
PAN Bei-Cheng, SHI Qing-Fan, SUN Gang
Chin. Phys. Lett. 2013, 30 (12): 124701 .   DOI: 10.1088/0256-307X/30/12/124701
Abstract   PDF(pc) (1255KB) ( 313 )
An experimental setup is developed to control a slow avalanche of a granular pile. The dynamical behavior of the quasi-static avalanche process is investigated systematically by directly tracking the displacement of particles in the avalanche. It is observed that the particles in the pile slide are in a layered structure, i.e., the pile can be divided into several parallel layers according to the displacement of the particles, at each layer the particles move with the same speed and in the same direction. The inclined angle of the layer is about 47°, which is also the direction of the movement of particles. We also find that there exists a critical layer below which the particles do not slide and above which the particles slide a lot, and the amount of its slippage is proportional to its distance from the critical layer.
PHYSICS OF GASES, PLASMAS, AND ELECTRIC DISCHARGES
Ultracold Neutral Plasma Produced by One-Color Two-Photon Ionization in Supersonic Nitric Oxide Molecular Beam
LI Hui, SHI Zhe, LIU Jin-Bo, GUO Jing-Wei, ZHOU Can-Hua, CAI Hong-Xing,CAI Xiang-Long
Chin. Phys. Lett. 2013, 30 (12): 125201 .   DOI: 10.1088/0256-307X/30/12/125201
Abstract   PDF(pc) (643KB) ( 253 )
Nitric oxide (NO) is cooled to 1 K in a seeded Ar supersonic molecular beam. NO molecules are ionized by one-color two-photon resonant enhanced multiphoton ionization (REMPI) process to form an ultracold plasma. The density of the ionized molecules in the illuminated volume approaches to 1.5 × 1013 cm?3. Prompt electrons, plasma electrons and intact NO+ ions are produced during this process. Experimental results confirm that the lifetime of this ultracold plasma is longer than 18.3 μs. This is the first report of NO ultracold plasma with significant lifetime produced by one-color two-photon REMPI process.
Numerical Simulations of Magnetic Reconnection in an Asymmetric Current Sheet
WANG Pei-Ran, HUANG Can, LU Quan-Ming, WANG Rong-Sheng, WANG Shui
Chin. Phys. Lett. 2013, 30 (12): 125202 .   DOI: 10.1088/0256-307X/30/12/125202
Abstract   PDF(pc) (948KB) ( 306 )
Previous particle-in-cell simulations have shown that electron phase-space holes (electron holes), where the associated parallel electric field has a bipolar structure, exist near the four separatrices in anti-parallel magnetic reconnection. By performing two-dimensional (2-D) particle-in-cell (PIC) simulations, here we investigate magnetic reconnection in an asymmetric current sheet, with emphasis on the parallel electric field near the separatrices. Compared with magnetic reconnection in a symmetric current sheet, it is found that the parallel electric field with a bipolar structure only exists around the separatrices in the upper region with a lower density (upper separatrices). Such a bipolar structure of the parallel electric field is considered to be associated with electron holes resulting from the nonlinear evolution of the electron beam instability excited by the high-speed electron flow formed after their acceleration around the X line. The disappearance of the parallel electric field around the separatrices in the lower region with a higher density (lower separatrices) may be due to the transverse instability, which is unstable in a weak magnetized plasma.
CONDENSED MATTER: STRUCTURE, MECHANICAL AND THERMAL PROPERTIES
Cavity Swelling in Three Ferritic-Martensitic Steels Irradiated by 196 MeV Kr Ions
LI Yuan-Fei, SHEN Tie-Long, GAO Xing, YAO Cun-Feng, WEI Kong-Fang, SUN Jian-Rong, LI Bing-Sheng, ZHU Ya-Bin, PANG Li-Long, CUI Ming-Huan, CHANG Hai-Long, WANG Ji, ZHU Hui-Ping, HU Bi-Tao, WANG Zhi-Guang
Chin. Phys. Lett. 2013, 30 (12): 126101 .   DOI: 10.1088/0256-307X/30/12/126101
Abstract   PDF(pc) (770KB) ( 361 )
We report on cavity swelling at peak damage regions of three ferritic-martensitic (FM) steels (NHS, RAFM and T91) irradiated by 196 MeV Kr ions at different temperatures (450/550°C). Cavity configurations of the irradiated specimens are investigated by transmission electron microscopy with cross-section technique. For home-made reduced activation ferritic-martensitic (RAFM) and T91 steels irradiated at 450°C, both large size and bimodal size distribution of the cavity are found in their peak damage regions, whereas novel high silicon (NHS) steel exhibits good swelling resistance at different irradiation temperatures. Temperature relativity of the cavity swelling in NHS, RAFM and T91 steels is discussed briefly.
A Local Statistical Structural Model for Amorphous Solids
SUN Qiang
Chin. Phys. Lett. 2013, 30 (12): 126102 .   DOI: 10.1088/0256-307X/30/12/126102
Abstract   PDF(pc) (512KB) ( 370 )
From Raman spectroscopic study on OH stretching bands, the local statistical interpretation for water structure is proposed. Due to the closely structural relationship between amorphous solids and liquids, the structural model is extended to investigate the amorphous solids, which indicates that various intensity of potential can be expected around an atom (molecule). From this, a local statistical order parameter is proposed to understand the short-range order and long-range disorder. The order parameter is influenced by the cooling rate in the glass formation, which means that glass is formed with a slower cooling rate, and has higher structural order. For amorphous solids, the geometric topology is closely related to chemical bonding type, such as covalent bond and metallic bond.
Pseudo Spin Torque Induced by Strain Field of Dirac Fermions in Graphene
Bumned Soodchomshom
Chin. Phys. Lett. 2013, 30 (12): 126201 .   DOI: 10.1088/0256-307X/30/12/126201
Abstract   PDF(pc) (492KB) ( 316 )
The physical property of pseudo spin of electrons in graphene is investigated. In contrast to a recent description [Phys. Rev. Lett. 106 (2011) 116803], we show that pseudo spin in graphene is not completely a real angular momentum. The pseudo spin only in the direction perpendicular to the graphene sheet is real angular momentum while the pseudo spin parallel to the graphene plane is still not real angular momentum. Interestingly, it is also shown that the Newtonian-like force and pseudo spin torque of massive Dirac electrons in graphene under strain field mimic gravitomagnetic force and gravitomagnetic spin torque, respectively. This is due to the equivalence of pseudo spin and velocity operators of (2+1)-dimensional massive electrons in graphene, different from that in real (3+1)-dimensional Dirac fields. This work reveals the new physical property of graphene as a pseudo gravitomagnetic material.
A Device for Measuring the Density and Liquidus Temperature of Molten Fluorides for Heat Transfer and Storage
CHENG Jin-Hui, ZHANG Peng, AN Xue-Hui, WANG Kun, ZUO Yong, YAN Heng-Wei, LI Zhong
Chin. Phys. Lett. 2013, 30 (12): 126501 .   DOI: 10.1088/0256-307X/30/12/126501
Abstract   PDF(pc) (548KB) ( 514 )
An experimental device is constructed for measuring the density and liquidus temperature of molten fluorides by using the Archimedean and cooling curve methods respectively. Its operation is tested by measuring the density and liquidus temperature of NaCl salt. The accuracy of the liquidus temperature measurement is about ±1 K. The density of NaCl measured is in good agreement with the widely recognized data and the deviation is less than 0.2%. The liquidus temperature and density of a typical heat transfer fluoride LiF-NaF-KF (46.5-11.5-42mol%) are investigated.
A Negative Thermal Expansion Material of ZrMgMo3O12
SONG Wen-Bo, LIANG Er-Jun, LIU Xian-Sheng, LI Zhi-Yuan, YUAN Bao-He, WANG Jun-Qiao
Chin. Phys. Lett. 2013, 30 (12): 126502 .   DOI: 10.1088/0256-307X/30/12/126502
Abstract   PDF(pc) (729KB) ( 551 )
A material with the formula ZrMgMo3O12 having negative thermal expansion is presented and characterized. It is shown that ZrMgMo3O12 crystallizes in an orthorhombic symmetry with space group Pnma(62) or Pna21(33) and exhibits negative thermal expansion in a large temperature range (αl=?3.8×10?6 K?1 from 300 K to 1000 K by x-ray diffraction and αl =?3.73×10?6 K?1 from 295 K to 775 K by dilatometer). ZrMgMo3O12 remains the orthorhombic structure without phase transition or decomposition at least from 123 K to 1200 K and is not hygroscopic. These properties make it an excellent material with negative thermal expansion for a variety of applications.
The Propulsion of a Miniature Device by Organic Fluid Jetflow through Polymer Submicron Tubes
WANG Yong-Xin, CHEN Yang, TAN Shuai-Xia, LI Yan-Fang, ZHAO Ning, XU Jian, ZHANG Li-Na
Chin. Phys. Lett. 2013, 30 (12): 126801 .   DOI: 10.1088/0256-307X/30/12/126801
Abstract   PDF(pc) (705KB) ( 331 )
A miniature device composed of anodic aluminum oxide membrane and aligned polypropylene submicron tubes is fabricated by a simple template method. When organic fluids are dripped on the membrane, the device floating on water could be propelled by organic fluid jetflow through the polymer tubes. The driving force is mainly attributed to the spreading of organic fluids on water surface. Compared to the motions driven by spreading fluids in bulk, the propulsion of this device is more efficient benefiting from the submicron-tube microstructure. This work may provide a feasible approach to enhance the efficiency of chemical driving movements.
CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES
Optoelectronic Properties of Pure and Co Doped Indium Oxide by Hubbard and modified Becke–Johnson Exchange Potentials
H. A. Rahnamaye Aliabad, M. Bazrafshan, H. Vaezi, Masood Yousaf, Junaid Munir, M. A. Saeed
Chin. Phys. Lett. 2013, 30 (12): 127101 .   DOI: 10.1088/0256-307X/30/12/127101
Abstract   PDF(pc) (1373KB) ( 748 )
Structural and optoelectronic properties of pure and Co doped In2O3 are studied by employing the full-potential linearized augmented plane wave method, which is known to produce highly accurate results. First principles calculations are performed with ordinary generalized gradient approximation (GGA) along with new Hubbard and modified Becke–Johnson exchange (mBJ) potential techniques. Improved band gap results are obtained for In2O3 with GGA+U and mBJ. In the case of mBJ, the band gap values are 3.5 eV and 3.4 eV for rhombohedral and cubic phases, which are in close agreement with the experimental data. Substitution of In by Co 25% alters the energy gap and a spin splitting effect is observed in these phases. For the spin-up state, it remains semiconductor, whereas for the spin-down state it shows semimetallic behavior. The value of static refractive index n(0) is 1.74 for the cubic phase, while in rhombohedral phase the values of n(0) are 1.77 and 1.74 along xx and zz optical axes, respectively. The calculated optical properties conform anisotropy in the rhombohedral phase and these materials can be potential candidates for the optoelectronics applications.
A Novel Silicon-on-Insulator Super-Junction Lateral-Double-Diffused Metal-Oxide-Semiconductor Transistor with T-Dual Dielectric Buried Layers
WU Li-Juan, ZHANG Wen-Tong, ZHANG Bo, LI Zhao-Ji
Chin. Phys. Lett. 2013, 30 (12): 127102 .   DOI: 10.1088/0256-307X/30/12/127102
Abstract   PDF(pc) (844KB) ( 313 )
A novel silicon-on-insulator (SOI) high-voltage device of super-junction (SJ) lateral-double-diffused metal-oxide-semiconductor transistors (LDMOSTs) with T-dual dielectric buried layers (T-DBLs) is presented. The T-DBLs are formed by the first T-shaped dielectric layer and the second dielectric layer. A lot of holes are accumulated on the top interface of the second dielectric layer, which compensates for the charge imbalance of the surface N and P pillars, thus the substrate-assisted depletion (SAD) effect is eliminated in the new device. The electric field of the second dielectric buried layer, EI2, is enhanced by the interface charges, and the breakdown voltage Vbreakdown is increased. EI2=515 V/μm is obtained in the T-DBL SOI SJ. The Vbreakdown of the new device is increased from 124 V of the conventional SOI SJ to 302 V with a 15 μm length drift region. The specific on-resistance (Ron, sp) of the T-DBL SOI SJ is only 0.00865 Ω?cm2 and the FOM (FOM = V2breakdown/Ron, sp) is 10.54 MW/cm2.
Upconversion Emission Properties of Erbium- and Ytterbium-Doped Potassium Lithium Tantalate Niobate Ceramics
LI Lei, ZHOU Zhong-Xiang, YANG Wen-Long, LI Huan, WU Ye
Chin. Phys. Lett. 2013, 30 (12): 127103 .   DOI: 10.1088/0256-307X/30/12/127103
Abstract   PDF(pc) (813KB) ( 258 )

We investigate the luminescence properties of erbium-doped and erbium-ytterbium-codoped potassium lithium tantalate niobate ceramics prepared by the solid phasesyntheses method. The crystalline structure and surface morphology of these ceramics are tested by x-ray diffraction and scanning electron microscopy. The green, red, and near-infrared upconversion photoluminescence properties are analyzed by the steady-state spectra under 975 nm and 800 nm excitations. These ceramics arewell sintered and tetragonal tungsten type crystalline structure with the 4 mm point group and the P4bm space group. The Er3+ upconversion emission integrated intensities increase with theincrease in Er3+ ion concentration, while the green emissiondecreases with the increase in Yb3+ ion concentration under the 800 nm excitation. An effective energy back transfer process from the Er3+ 4S3/2 state to Yb3+ ground state plays an important role in enhancing the red emission and weakening the green emission.

First Principles Study on Elastic Constants, Ferromagnetism and Electronic Structures of Alloyed Fe3Si Doped with Mo, Ti or Nb
MA Rui, XIE Quan, HUANG Jin, GUO Xiao-Tian, YAN Wan-Jun
Chin. Phys. Lett. 2013, 30 (12): 127104 .   DOI: 10.1088/0256-307X/30/12/127104
Abstract   PDF(pc) (600KB) ( 329 )
Elastic constants, ferromagnetism and electronic structures of Fe11MoSi4, Fe11TiSi4, and Fe11NbSi4 are studied by first-principles calculations with density functional theory (DFT). It is found that the ductility of Fe3Si could be obviously improved with the addition of Ti. The G/B0 of Fe11TiSi4 is 0.483, which means that it is ductile. The strong interaction of Fe 3d–Ti 3d intensifies the metallic character. However, Fe11NbSi4 has the optimal ferromagnetism. The total magnetic moments of the Fe11NbSi4 is 20.42μB. The difference between spin-up electrons and spin-down electrons at the Fermi level markedly varies with different alloying elements; furthermore, the difference at EF in the Nb case is the highest.
AlGaN Channel High Electron Mobility Transistors with Ultra-Low Drain-Induced-Barrier-Lowering Coefficient
HA Wei, ZHANG Jin-Cheng, ZHAO Sheng-Lei, GE Sha-Sha, WEN Hui-Juan, ZHANG Chun-Fu, MA Xiao-Hua, HAO Yue
Chin. Phys. Lett. 2013, 30 (12): 127201 .   DOI: 10.1088/0256-307X/30/12/127201
Abstract   PDF(pc) (630KB) ( 553 )
The conventional AlGaN/GaN high electron mobility transistor (HEMT), the AlGaN/GaN/AlGaN HEMT, and the AlxGa1?xN/AlyGa1?yN HEMT are fabricated on sapphire substrates to study the drain-induced barrier-lowering (DIBL) effect. It is found that the AlxGa1?xN/AlyGa1?yN HEMT with AlGaN channel has the lowest DIBL coefficient of 6.7 mV/V compared with the other two HEMTs. This is attributed to the best two-dimensional electron gas confinement of the AlxGa1?xN/AlyGa1?yN structure. This opinion is further confirmed by the conduction band diagrams and electron distribution calculated from the one-dimensional Poisson–Schr?dinger equation.
High-Performance InTiZnO Thin-Film Transistors Deposited by Magnetron Sputtering
LIU Ao, LIU Guo-Xia, SHAN Fu-Kai, ZHU Hui-Hui, B. C. Shin, W. J. Lee, C. R. Cho
Chin. Phys. Lett. 2013, 30 (12): 127301 .   DOI: 10.1088/0256-307X/30/12/127301
Abstract   PDF(pc) (769KB) ( 570 )
InTiZnO thin-film transistors (ITZO TFTs) with Al2O3 gate dielectrics are fabricated by magnetron sputtering at room temperature. The bottom-gate-type ITZO TFTs with amorphous Al2O3 gate dielectrics are operated in the enhancement mode and exhibit a mobility of 50.4 cm2/V?s, threshold voltage of 1.2 V, subthreshold swing of 94.5 mV/decade, and on/off-current ratio of 7×106. We believe that ITZO deposited at room temperature is an appropriate semiconductor material to produce high-mobility TFTs for developing flexible electronic devices.
Interface States in AlGaN/GaN Metal-Insulator-Semiconductor High Electron Mobility Transistors
FENG Qian, DU Kai, LI Yu-Kun, SHI Peng, FENG Qing
Chin. Phys. Lett. 2013, 30 (12): 127302 .   DOI: 10.1088/0256-307X/30/12/127302
Abstract   PDF(pc) (701KB) ( 627 )
Frequency-dependent capacitance and conductance measurements are performed on AlGaN/GaN high electron mobility transistors (HEMTs) and NbAlO/AlGaN/GaN metal-insulator-semiconductor HEMTs (MISHEMTs) to extract density and time constants of the trap states at NbAlO/AlGaN interface and gate/AlGaN interface with the gate-voltage biased into the accumulation region and that at the AlGaN/GaN interface with the gate-voltage biased into the depletion region in different circuit models. The measurement results indicate that the trap density at NbAlO/AlGaN interface is about one order lower than that at gate/AlGaN interface while the trap density at AlGaN/GaN interface is in the same order, so the NbAlO film can passivate the AlGaN surface effectively, which is consistent with the current collapse results.
Electronic and Optical Properties of Spinel GeMg2O4 and GeCd2O4
A. Manzar, G. Murtaza, R. Khenata, S. Muhammad, Hayatullah
Chin. Phys. Lett. 2013, 30 (12): 127401 .   DOI: 10.1088/0256-307X/30/12/127401
Abstract   PDF(pc) (567KB) ( 271 )
Oxide spinels have potential applications in optoelectronics and optics fields. In this work the electronic band structure and optical properties of GeMg2O4 and GeCd2O4 are calculated by first principles technique based on the new potential approximation known as the modified Becke–Johnson exchange potential approximation (mBJ). The local density and generalized gradient approximations significantly underestimate the direct band gap values compared to the mBJ. The band gap dependent optical parameters such as dielectric constant, refractive index, reflectivity and optical conductivity are calculated and analyzed. The replacement of the cation is observed and analyzed for the compounds studied and a prominent change is noticed. The replacement of the cation Mg by Cd reduces the band gap and its dependent optical parameters. For device fabrication in different regions of the spectrum this variation is strongly recommended.
Fermi Surface and Band Structure of (Ca,La)FeAs2 Superconductor from Angle-Resolved Photoemission Spectroscopy
LIU Xu, LIU De-Fa, ZHAO Lin, GUO Qi, MU Qing-Ge, CHEN Dong-Yun, SHEN Bing, YI He-Mian, HUANG Jian-Wei, HE Jun-Feng, PENG Ying-Ying, LIU Yan, HE Shao-Long, LIU Guo-Dong, DONG Xiao-Li, ZHANG Jun, CHEN Chuang-Tian, XU Zu-Yan, REN Zhi-An, ZHOU Xing-Jiang
Chin. Phys. Lett. 2013, 30 (12): 127402 .   DOI: 10.1088/0256-307X/30/12/127402
Abstract   PDF(pc) (3986KB) ( 709 )

The (Ca,R)FeAs2 (R=La, Pr, etc.) superconductors with a signature of superconductivity transition above 40 K possess a new kind of block layers that consist of zig-zag As chains. We report the electronic structure of the new (Ca,La)FeAs2 superconductor investigated by both band structure calculations and high resolution angle-resolved photoemission spectroscopy measurements. Band structure calculations indicate that there are four hole-like bands around the zone center Γ(0,0) and two electron-like bands near the zone corner M(π, π) in CaFeAs2. In our angle-resolved photoemission measurements on (Ca0.9La0.1)FeAs2, we have observed three hole-like bands around the Γ point and one electron-like Fermi surface near the M(π, π) point. These results provide important information to compare and contrast with the electronic structure of other iron-based compounds in understanding the superconductivity mechanism in the iron-based superconductors.

Influence of Orthorhombic-Tetragonal Phase Transition on Microwave Dielectric Dispersion of BaTiO3 Ceramic
HAO Wen-Tao, ZHANG Jia-Liang, ZHENG Peng, WU Yan-Qing, TAN Yong-Qiang, ZHAO Xu
Chin. Phys. Lett. 2013, 30 (12): 127701 .   DOI: 10.1088/0256-307X/30/12/127701
Abstract   PDF(pc) (768KB) ( 377 )
The temperature evolution of dielectric dispersion is examined for a coarse-grained BaTiO3 ceramic in the frequency range from 40 Hz to 1 GHz and over the temperature interval between ?50°C and 80°C, which thus includes the orthorhombic-tetragonal phase transition and covers the large part of common usage temperature region. We find an important physical phenomenon that the phase transition has a notable influence on the microwave dielectric dispersion. The dielectric permittivity ε' shows a maximum, whereas the characteristic frequency fr displays a minimum in the vicinity of orthorhombic-tetragonal phase transition temperature. Also, a large difference in the fr values is observed in the tetragonal phase between the heating process and the cooling process. It seems that the experimentally found phenomenon can be explained by the previously suggested mechanism of the emission of elastic shear waves from ferroelastic domain walls.
Polarization Switching Induced Decrease of Bulk Resistivity in Ferroelectric Pb(Zr0.45Ti0.55)O3 Thin Films and a Method to Improve Their Fatigue Endurance
ZHU Hui, CHU Da-Ping
Chin. Phys. Lett. 2013, 30 (12): 127702 .   DOI: 10.1088/0256-307X/30/12/127702
Abstract   PDF(pc) (651KB) ( 254 )
Significant reduction of the bulk resistivity in a ferroelectric Pb(Zr0.45Ti0.55)O3 thin film is observed before the remnant polarization started to decrease noticeably at the onset of its fatigue switching process. It is associated with the increase of charge carriers within the central bulk region of the film. The decrease of bulk resistivity would result in the increase of Joule heating effect, improving the temperature of the thin film, which is evaluated by the heat conduction analysis. The Joule heating effect in turn accelerates the polarization reduction, i.e. fatigue. Enhancing the heat dissipation of a ferroelectric capacitor is shown to be able to improve the device's fatigue endurance effectively.
Temperature-Induced Plasma Frequency Shift in Bi2Te3 and CuxBi2Se3
DONG Tao, YUAN Rui-Hua, SHI You-Guo, WANG Nan-Lin
Chin. Phys. Lett. 2013, 30 (12): 127801 .   DOI: 10.1088/0256-307X/30/12/127801
Abstract   PDF(pc) (613KB) ( 269 )
We present an optical spectroscopy study on Bi2Se3, Bi2Te3, Sn-doped Bi2Te3 and Cu-intercalated Bi2Se3 crystals grown by self-melting. We find that the plasma edge of Bi2Se3 slightly shifts to lower energy with decreasing temperature. The Cu-intercalated Bi2Se3 shows a superconducting transition near 3.1 K. Optical spectroscopy measurement shows that the plasma edge shifts substantially to higher frequency 1250 cm?1 indicating that Cu-doping supplies extra electrons to the system and further shifts the chemical potential up. Furthermore, our measurement reveals that the plasma edge of Bi2Te3, Sn doped Bi2Te3Snδ(δ=0.67%) and Cu-intercalated Bi2Se3 shift slightly to higher energies with decreasing temperature. Combined with the band calculation, we attribute the blue-shift primarily to the reduction of effective mass of carriers with decreasing temperature. The optical data yield useful information about the bulk electronic band structure of the superconducting doped topological insulator CuxBi2Se3 (x=0.14).
CROSS-DISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY
Fast Homoepitaxial Growth of 4H-SiC Films on 4° off-Axis Substrates in a SiH4-C2H4-H2 System
LIU Bin, SUN Guo-Sheng, LIU Xing-Fang, ZHANG Feng, DONG Lin, ZHENG Liu, YAN Guo-Guo, LIU Sheng-Bei, ZHAO Wan-Shun, WANG Lei, ZENG Yi-Ping, LI Xi-Guang, WANG Zhan-Guo, YANG Fei
Chin. Phys. Lett. 2013, 30 (12): 128101 .   DOI: 10.1088/0256-307X/30/12/128101
Abstract   PDF(pc) (1558KB) ( 383 )
Homoepitaxial growth of 4H-SiC epilayers is conducted in a SiH4-C2H4-H2 system by low pressure hot-wall vertical chemical vapor deposition (CVD). Thick epilayers of 45 μm are achieved at a high growth rate up to 26 μm/h under an optimized growth condition, and are characterized by using a Normaski optical microscope, a scanning electronic microscope (SEM), an atomic force microscope (AFM) and an x-ray diffractometer (XRD), indicating good crystalline quality with mirror-like smooth surfaces and an rms roughness of 0.9 nm in a 5 μm × 5μm area. The dependence of the 4H-SiC growth rate on growth conditions on 4° off-axis 4H-SiC substrates and its mechanism are investigated. It is found that the H2 flow rate could influence the surface roughness, while good surface morphologies without Si droplets and epitaxial defects such as triangular defects could be obtained by increasing temperature.
Impact of Au Nanocrystal Size and Inter-Nanocrystal Distance on the Storage Characteristics of Memory Devices
LAN Xue-Xin, OU Xin, XU Bo, GONG Chang-Jie, LI Run, YIN Qiao-Nan, XIA Yi-Dong, YIN Jiang, LIU Zhi-Guo, LI Ai-Dong, YAN Feng
Chin. Phys. Lett. 2013, 30 (12): 128102 .   DOI: 10.1088/0256-307X/30/12/128102
Abstract   PDF(pc) (1192KB) ( 245 )
The charge-storage characteristics of charge trapping memory devices containing different sizes of Au nanocrystals (NCs) sandwiched by Al2O3 tunneling and blocking layers are studied. A strong impact of both Au NC size and inter-NC distance on the charge trapping capability of the devices is observed. The total surface area of Au NCs associated with Au NC size is supposed to be a key factor in the charge-storage capability, and the device with larger size of Au NCs and a suitable inter-NC distance will possess better charge trapping capability. Variable range hopping as the lateral charge loss mechanism is considered as the main reason for the decrease of the charge trapping capability when Au NCs grow and overlap neighbors.
Eco-Friendly Phyto-Synthesis of Silver Nanoparticles Using Jatropha Seedcake Extract
Anjali Bose, Haresh Keharia, M. P. Deshpande
Chin. Phys. Lett. 2013, 30 (12): 128103 .   DOI: 10.1088/0256-307X/30/12/128103
Abstract   PDF(pc) (1007KB) ( 586 )
Phytosynthesis of metal nanoparticles is gaining importance due to their biocompatibility, low toxicity and eco-friendly nature. In the present study, an aqueous extract of Jatropha seedcake (JSC) is assessed as a reducing and stabilizing agent for the synthesis of silver nanoparticles (AgNPs). The maximum reduction of silver ions occur when 1 mM AgNO3 solution is treated with 0.1 volume fraction of JSC extract in boiling water bath for 10 min. The synthesis of AgNPs is monitored by the excitation of surface plasmon resonance using UV-vis spectrophotometry. The AgNPs are found to be mono-dispersed, spherical with average particle size of 10.48 ± 74 nm when analyzed by transmission electron microscopy. The selected area electron diffraction (SAED) ring pattern indicated the polycrystalline nature of the AgNPs. The x-ray diffraction data further confirm the presence of characteristic (111), (200), (220), (311) and (222) diffraction planes of face centered cubic structure, and the calculated lattice parameter comes out to be 4.083 ?. FTIR analysis reveals the involvement of proteins and phenols in reduction and stabilization of nanoparticles. The synthesized AgNPs have significant antibacterial action on both the Gram positive and negative bacteria.
Frequency Gradient with Respect to Temperature for Determination of Classification of the Phase Response Curve
Yasuomi D. Sato
Chin. Phys. Lett. 2013, 30 (12): 128201 .   DOI: 10.1088/0256-307X/30/12/128201
Abstract   PDF(pc) (1168KB) ( 270 )
The interesting task here is to study the frequency-current (fI) curve and phase response curve (PRC), subject to neural temperature variations, because the fI curve and PRC are important measurements to understand dynamical mechanisms of generation of neural oscillations, and the neural temperature is widely known to significantly affect the oscillations. Nevertheless, little is discussed about how the temperature affects the fI curve and PRC. In this study, frequencies of the neural oscillations, modulated with the temperature variations, are quantified with an average of the PRC. The frequency gradient with respect to temperature derived here gives clear classifications of the PRC, regardless of the form. It is also indicated that frequency decreases with an increase in temperature, resulted from bifurcation switching of the saddle-homoclinic to the saddle-node on an invariant circle.
Magnetic-Particle-Composite-Medium-Filled Stacked-Spiral Inductors for Radio-Frequency CMOS Applications
ZHAN Jing, CAI Hua-Lin, CHEN Xiao, WANG Xin, FANG Qiang, YANG Yi, REN Tian-Ling, LIU Li-Tian, LI Xin-Xin, WANG Albert, YANG Chen
Chin. Phys. Lett. 2013, 30 (12): 128401 .   DOI: 10.1088/0256-307X/30/12/128401
Abstract   PDF(pc) (1271KB) ( 320 )
Magnetic-particle-composite-medium-filled stacked-spiral inductors for rf complementary metal oxide semiconductor (CMOS) applications in GHz are demonstrated. The new inductor features a nearly closed magnetic circuit loop, an optimized high-permeability and low-loss sub-1 μm magnetic particles' composite core, and a developed 0.18-μm CMOS-compatible device fabrication process. An equivalent circuit model with structural amplifying factors is proposed and modeled. The prototype of the 6-level stacked inductor with Co2Z magnetic-particles-composite-medium filling increases the inductance L by 50%, and quality factor Q by 37% at frequencies as high as 1 GHz, with high inductance density as 825 nH/mm2 and a reduced size area by 80% compared to the planar spiral inductor.
Enhanced Performance in Perovskite Organic Lead Iodide Heterojunction Solar Cells with Metal-Insulator-Semiconductor Back Contact
HI Jiang-Jian, DONG Wan, XU Yu-Zhuan, LI Chun-Hui, LV Song-Tao, ZHU Li-Feng, DONG Juan, LUO Yan-Hong, LI Dong-Mei, MENG Qing-Bo, CHEN Qiang
Chin. Phys. Lett. 2013, 30 (12): 128402 .   DOI: 10.1088/0256-307X/30/12/128402
Abstract   PDF(pc) (697KB) ( 3150 )

Metal-insulator-semiconductor back contact has been employed for a perovskite organic lead iodide heterojunction solar cell, in which an ultrathin Al2O3 film as an insulating layer was deposited onto the CH3NH3PbI3 by atomic layer deposition technology. The light-to-electricity conversion efficiency of the devices is significantly enhanced from 3.30% to 5.07%. Further the impedance spectrum reveals that this insulating layer sustains part of the positive bias applied in the absorber region close to the back contact and decreases the carrier transport barrier, thus promoting transportation of carriers.

Sub-Wavelength Near-Field Metal Detection using an On-Chip Spintronic Technique
WANG Qi, ZHU Xiao-Feng, YUAN Xiao-Wen, CHEN Chang-Qing, LUO Xiang-Dong, ZHANG Bo
Chin. Phys. Lett. 2013, 30 (12): 128501 .   DOI: 10.1088/0256-307X/30/12/128501
Abstract   PDF(pc) (692KB) ( 291 )
A spintronic near-field microwave imaging system without vector network analyzers is used to detect the distribution of microwaves, which are scattered by a sub-wavelength periodical metal wire grating. An ultra thin metal body with diameter of 100 μm (λ/300) is observed by imaging illuminated by a 10 GHz shining source. An application with high sensitivity and resolution detection is proposed in the microwave region under a weak applied external static magnetic field.
Local Compression Properties of Double-Stranded DNA Based on a Dynamic Simulation
LEI Xiao-Ling, QI Wen-Peng, FANG Hai-Ping
Chin. Phys. Lett. 2013, 30 (12): 128701 .   DOI: 10.1088/0256-307X/30/12/128701
Abstract   PDF(pc) (1002KB) ( 272 )
Using a simple sphere-tip compression system, the local radial mechanical properties of DNA are systematically studied by changing the tip size. When the tip size decreases, the radial compression elastic properties under external loads become sensitive to the tip size and the local DNA conformation. A sudden force break appears in the compression-force curve when the tip size is less than or equal to 12 nm in diameter. The analysis of the hydrogen bonds and the base stacking interaction shows that a local unwinding process occurs. During the compression process, firstly the hydrogen bonds between complement base pairs are broken. With the compression accumulating, the local backbones in the compression center are unwound from the double helix conformation to a kind of parallel conformation. This local unwinding behavior deduced by external loads is helpful to understand the biological process and is important to DNA-based nanomechanical devices.
GEOPHYSICS, ASTRONOMY, AND ASTROPHYSICS
The Nucleon Direct Urca Processes in a Cooling Neutron Star
XU Yan, LIU Guang-Zhou, LIU Cheng-Zhi, FAN Cun-Bo, WANG Hong-Yan, ZHU Ming-Feng, ZHAO En-Guang
Chin. Phys. Lett. 2013, 30 (12): 129501 .   DOI: 10.1088/0256-307X/30/12/129501
Abstract   PDF(pc) (632KB) ( 308 )
In the relativistic mean field approximation, the relativistic energy losses of the nucleon direct Urca processes are studied in the degenerate baryon matter of neutron stars. We investigate the effects of hyperon degrees of freedom and the isovector scalar interaction which is considered by exchanging δ meson on the nucleon direct Urca processes in neutron star matter. The results indicate that the existence of hyperons decreases the abundance of protons and leptons and can sharply suppress the neutrino emissivity of the nucleon direct Urca processes, while it has only a little influence on the neutrino luminosity for a fixed neutron star whether δ mesons appear in a neutron star or not. However, the presence of δ mesons can result in obvious growth in the neutrino emissivity and luminosity which will speed up the cooling rate for the nonsuperfluid neutron star.
47 articles