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Volume 14 Issue 2
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Original Articles
Thermodynamics of a Static Dilaton Black Hole
JING Ji-liang
Chin. Phys. Lett. 1997, 14 (2): 81-84 .  
Abstract   PDF(pc) (200KB) ( 502 )
The thermodynamics of a static dilaton black hole is investigated by Euclidean path integral. Four interesting results are obtained: (I) Although the temperature, heat capacity and chemical potential have different forms as compared to general classical static charged black hole, the Bardeen-Carter-Hawking thermodynamical laws are valid for the black hole. (II) The entropy and area of the event horizon are zero but the energy, temperature and surface gravity are non-zero for extremal case ( rh = 2M = b). (III) The charged black hole does not possess second order phase transitions as the Reissner-Nordström black hole since its heat capacity is negative. (IV) The action is equal to the entropy, and both quantities coincide with one quarter of area of the event horizon.

Finding and Control of Unstable Periodic Orbit in Autonomous Differential System
LIU Zong-hua, CHEN Shi-gang
Chin. Phys. Lett. 1997, 14 (2): 85-88 .  
Abstract   PDF(pc) (218KB) ( 394 )
A new method used to control unstable periodic orbit is presented. This method can reduce the three-dimensional system into two-dimensional by considering an appropriate variable equation as free equation. It is also effective in the presence of noise.
Phase Structure of Strange Matter in a Non-topological Soliton Model
ZHANG Yi-jun, GAO Song, HE Yong-bin, SU Ru-keng, LI Xue-qian
Chin. Phys. Lett. 1997, 14 (2): 89-92 .  
Abstract   PDF(pc) (242KB) ( 443 )
A non-topological soliton model with strange quarks is suggested to investigate the phase structure of strange matter. The results are qualitatively in agreement with that obtained by MIT bag model provided the ratio of coupling constants of different quarks to soliton scalar field xσ ≡ g/g larger than a critical value xc ~ 0.86, but as xσ gets smaller than xc, the phase structure may change.

Image of Ne Trap by a Microwave Cavity
XU Lei, Satoshi Oishi, Kazuko Shimizu, Hiroshi Takuma, Fujio Shimizu
Chin. Phys. Lett. 1997, 14 (2): 93-95 .  
Abstract   PDF(pc) (194KB) ( 479 )
The focusing of Ne metastable atoms trapped in magnetic-optical trap by a microwave cavity was demonstrated. The cavity was operated at TM010 mode. With a microwave power of 14W , the Ne trap was imaged to a spot of about 0.25mm (full width at half maximum value) which is nearly the geometric-optics limit.
Dispersion of Ultrafast Optical Kerr Effect in No-aggregation Phthalocyanine Molecules
GONG Qi-huang, T. Isoshima, M. Q. Tian, T. Wada, H. Sasabe
Chin. Phys. Lett. 1997, 14 (2): 96-99 .  
Abstract   PDF(pc) (216KB) ( 482 )
We report dispersion property for femtosecond optical Kerr effect in the solutions of no-aggregation 16 (trifluoro ethoxy1) vanadyl phthalocyanine in the wavelength range of 850-770 nm. The optical Kerr effect spectrum shows a broad near-resonant enhancement on the third-order nonlinear optical response of the molecule.
Hysteresis Loop of Energy Transfer in Two-Wave Mixing from 180°Domains in BaTiO3:Ce
WU Jian-lao, DAI Jian-hua, ZHANG Hong-jun
Chin. Phys. Lett. 1997, 14 (2): 100-102 .  
Abstract   PDF(pc) (150KB) ( 380 )
This paper reports an experimental observation that a hysteresis loop of energy transfer versus an external electric field is obtained in photorefractive two-wave mixing, which originates from 180°domains presented in the crystal.
Improvement of the Two-Beam Coupling Response Time in Photorefractive Double-Doping KNbO3
ZHANG Zhi-guo, Y. Ding, H. J . Eichler, FU Pan-ming, ZHOU Gang, TANG Jun-xiong, SHEN De-zhong, MA Xiao-yan, CHEN Jiong-yao
Chin. Phys. Lett. 1997, 14 (2): 103-105 .  
Abstract   PDF(pc) (214KB) ( 520 )
We report experimental studies on the photorefractive response of KNbO3 doubly doped with manganese and rubidium, iron and rubidium, respectively. Two- beam coupling response time in KNbO3:Mn:Rb is 3 to 10 times shorter while the two-beam coupling gain coefficient remains almost the same when compare with that in KNbO3 :Mn. On the other hand, under similar conditions, two-beam coupling response time in KNbO3 :Fe:Rb is 6 times faster than that in KNbO3 :Fe.
Silicon-on-Insulator 2 × 2 Symmetric Optical Switch Based on Total Internal Reflection
ZHAO Ce-zhou, LIU En-ke, LI Guo-zheng, LIU Yu-liang, GUO Lin
Chin. Phys. Lett. 1997, 14 (2): 106-108 .  
Abstract   PDF(pc) (222KB) ( 483 )
Based on the large cross-section single-mode rib waveguide condition, the total internal reflection and the free-carrier plasma dispersion effect, a silicon-on-insulator (SOI) 2 × 2 symmetric optical waveguide switch with a transverse injection structure has been proposed and fabricated, in which the SOI technique utilizes silicon and silicon dioxide thermal bonding and back-polishing. The device performance is measured at the wavelength of 1.3μm. It shows that the crosstalk and insertion loss are less than -18.1 and 4.8 dB, respectively, at an injection current of 60mA, and response time is 110 ns.

Dynamics of Soliton-Soliton Interactions in Parametrically-Driven Systems
WANG Xin-long
Chin. Phys. Lett. 1997, 14 (2): 109-112 .  
Abstract   PDF(pc) (244KB) ( 513 )
The parametrically-driven, damped nonlinear Schrödinger equation is numerically investigated and the parameter regions for the double-solitons of like polarity are found. The simulations of the soliton evolution in the parameter regions are in good agreement with the experimental observations. The computations also reveal that the “particles number”, momentum and energy are no more constants but vary in a periodic fashion in the system.
Conservation and Density Wave Equations of Plasma in Presence of Intense Laser Field
LIU Shi-bing, CHEN Shi-gang
Chin. Phys. Lett. 1997, 14 (2): 113-116 .  
Abstract   PDF(pc) (255KB) ( 402 )
The pressure tensor, energy density, and conservation equations of plasma in an intense laser field are derived by using a nonequilibrium distribution function. The results show that the effect of the intense laser field on the behavior of plasma cannot be neglected. As an application, the adiabatic equation of state, electronic density wave equation, and relevant dispersion relation are obtained for the electrostatic wave behavior. A substitution relation of the conserwtion equations from weak to intense field limits are presented.
Microwave Generation from an Oscillating Virtual Cathode Produced by Non-homogeneous Electron Beams
LIU Jin-liang, ZHANG Ya-zhou, LI Chuan-lu, TAN Qi-mei, CHEN Guo-qiang, WANG Yong
Chin. Phys. Lett. 1997, 14 (2): 117-120 .  
Abstract   PDF(pc) (205KB) ( 417 )
Microwave generation from a resonant cavity surrounding oscillating virtual cathode, which is produced by non-homogeneous electron beams, is studied experimentally. The microwave power is measured by using the crystal detector and frequencies are measured by using the heterodyne technique. A single microwave pulse contains two microwave signals with different frequencies, one peak power is 1.12MW at 5.03GHz and the other is 0.56MW at 5.24GHz, and their 3dB bandwidths are 18 and 25 MHz, respectively.
Magic Angular Momenta of a Spin-Aligned 6-Electron Quantum Dot
BAO Cheng-guang, RUAN Wen-ying, LIU You-yan, ZHANG Zhao-qing
Chin. Phys. Lett. 1997, 14 (2): 121-123 .  
Abstract   PDF(pc) (35KB) ( 469 )
The low-lying states of a spin-aligned 6-electron quantum dot may prefer the regular hexagon and regular centered pentagon structures. However, these favourable structures may be prohibited by inherent symmetry. Based on this consideration, a couple of equations are deduced. The solution of these equations gives exactly the magic numbers of the 6-electron dot.
Junction Current Drift Effect of the Cu/Porous Si Device Prepared by Electrodeposition
WANG Guan-zhong, LI Peng, MA Yu-rong, FANG Rong-chuan
Chin. Phys. Lett. 1997, 14 (2): 124-126 .  
Abstract   PDF(pc) (242KB) ( 458 )
A novel characteristic of the junction current drift effect in the Cu/porous silicon (Cu/PS) device prepared by electrodeposition in which Cu ions were deposited on porous silicon is reported. The junction current increases with time and gradually approaches to a saturated value when a certain forward bias is applied on the Cu/PS device. Moreover, after the bias was withdrawn for a period, a different drift process was observed when the same bias was applied again. The drifttime constant and the initial current of latter drift process depend on cut-off time. Such an effect is explained in terms of the model that only part of electrons from porous silicon contributes to the junction current while other electrons are captured by the traps in the interface between Cu and porous silicon in the Cu/PS device.
Interface Electronic Structure of Ge/ZnSe( 111)
ZHANG Hai-feng, WANG Chong-yu, FANG Rong-chuan, BAN Da-yan, LI Yong-ping
Chin. Phys. Lett. 1997, 14 (2): 128-130 .  
Abstract   PDF(pc) (180KB) ( 394 )
Using linear muffin-tin orbitals method with atomic sphere approximation, the interface electronic structure of Ge/ZnSe(111) has been studied. The density of states, local density of states as well as local partial density of states are presented. The interface electronic structure and the interaction characteristics between interface atoms are analyzed. The results show a significant effect of the interface atomic arrangement on the electronic structures.
Effect of AlN Film on the Magnetic Properties of Rare Earth-Transition Metal Film
LU Zheng-qi, LI Zuo-yi, ZHENG Yuan-kai, MIAO Xiang-shui, HU Zuo-qi, LIN Geng-qi, LIU Wei-zhong, XIONG Rui, WANG Ke
Chin. Phys. Lett. 1997, 14 (2): 131-133 .  
Abstract   PDF(pc) (175KB) ( 515 )
The amorphous TbFeCo films covered with the protective AIN films have been prepared by the rf magnetron sputtering system. It is found that the protective AIN films not only protect rare earth elements from oxidation and enhance magneto-optical Kerr effect but also affect the magnetic properties of the rare earth-transition metal films. The coercivity Hc and perpendicular magnetic anisotropy energy constants K'U1 and KU2 of the films are changed with the thickness of the protective AIN films. It can be explained according to the stress mechanism and the model of single ion anisotropy.
Atomic Force Microscopy Studies of Barium Titanate Thin Films Prepared by Laser Molecular Beam Epitaxy
CUI Da-fu, LÜ, Hui-bin, WANG Hui-sheng, CHEN Zheng-hao, ZHOU Yue-liang, YANG Guo-zhen, YANG Hai-tao, TAO Hong-jie, LI Lin
Chin. Phys. Lett. 1997, 14 (2): 134-137 .  
Abstract   PDF(pc) (207KB) ( 438 )
Laser molecular beam epitaxy (laser MBE) technique was utilized to grow the barium titanate (BaTiO3, BTO) thin films on SrTiO3(100) substrates. The surface morphology of the BaTiO3 thin films was studied by atomic force microscopy (AFM). Two- and three-dimensional AFM images were obtained. The root mean square surface roughness, the height profile, the histogram and the bearing ratio of the height distributions for the BaTiO3 thin films were analyzed in detail. The results indicate that the laser MBE thin films exhibit an atomically smooth surface.
Sensitivity of the Ag/SiO2 Mesoporous Composite on Ambiences in the Optical Absorption
CAI Wei-ping, ZHANG Li-de
Chin. Phys. Lett. 1997, 14 (2): 138-140 .  
Abstract   PDF(pc) (340KB) ( 490 )
The influence of ambient conditions on the optical absorption has been investigated for the porous silica dispersed with silver nano-particles (about 3nm) within its pores. It has been shown that in the process of alternative exposure to the ambience and annealing, this new material assumes the optical memory effect and the reversible transition between the transparency and opacity in the visible wave band.
Enhancement of Electroluminescence by Low-Temperature Deposition of Organic Thin Solid Films
GU Jian-hua, XU Min-hua, XIAO Zhong-dang, LU Zu-hong, HUANG Song-yu
Chin. Phys. Lett. 1997, 14 (2): 141-144 .  
Abstract   PDF(pc) (206KB) ( 430 )
The electrical and light-emitting behaviors of electroluminescent cells, which consist of naphthoylimide (NPL) as emitting layer and poly(3-octylthiophene)(P3OT) doped with poly(N-vinylcarbazoe) (PVK) as hole transport layer sandwiched between indium-tin-oxide(ITO) and aluminum electrode, have been studied. The mixed polymer (P3OT:PVK) layer and the emitting layer were deposited by spin coating and by vacuum deposition respectively. It was found that the visible blue emission could be observed from the cells at low bias voltage. And when the ITO substrate was cooled to near the liquid N2 temperature during the deposition of NPL emitting layer, the brightness of the cell increased. It was confirmed that holes could be easily injected into NPL layer with deposition temperature decreased.
Interfacial Structure Between Epitaxial Diamond Films and Silicon Substrates
GAO Qiao-jun, YOU Li-ping, PAN Xiao-hui, ZHANG Fan, PENG Xiao-fu, LIN Zeng-dong
Chin. Phys. Lett. 1997, 14 (2): 145-147 .  
Abstract   PDF(pc) (195KB) ( 502 )
Epitaxial diamond films on non-mirror polished silicon substrate was achieved using hot filament chemical vapor deposition method with one flat horizontal filament. The orientation relationship of epitaxial diamond films on silicon substrate has been investigated by cross-sectional high-resolution transmission electron microscopy We found one excellent epitaxial configuration and according to the experimental result we suggest a corresponding model. The lattice misfit is only 0.1-2.8% related to our model and the analysis of 60°type interface dislocation also supports this model.

Giant Magnetoresistance and Microstructure of Melt-Spun Cu70Co30 Ribbons
SONG Xiao-ping, S. W. Mahon, R. F. Cochrane, B. J. Hickey, M. A. Howson
Chin. Phys. Lett. 1997, 14 (2): 148-150 .  
Abstract   PDF(pc) (184KB) ( 358 )
This paper reports an investigation on the giant magnetoresistance and microstructure evolution in melt-spun Cu70Co30alloy. The results show that the phase separation is inevitable in the course of quenching, leading to the formation of two types of fcc magnetic Co-rich particles but these do not appear to contribute to the magnetoresistance (MR). On annealing, a very fine distribution of Co-rich precipitates forms at temperatures above 573 K which are responsible for the high MR developed in this material.
Influence of the Size Distribution of Particles on the Viscous Property of an Electrorheological Fluid
WANG Zuo-wei, LIN Zhi-fang, TAO Rui-bao
Chin. Phys. Lett. 1997, 14 (2): 151-154 .  
Abstract   PDF(pc) (266KB) ( 456 )
The influence of the size distribution of particles on the viscous property of an electrorheological fluid has been investigated by the molecular dynamic simulation method. The shear stress of the fluid is found to decrease with the increase of the variance σ2 of the Gaussian distribution of the particle size, and then reach a steady value when σ is larger than 0.5. This phenomenon is attributed to the influence of the particle size distribution on the dynamic structural evolution in the fluid as well as the strength of the different chain-like structures formed by the particles.
Self-Microlensing in Compact Binary Systems
QIN Bo, WU Xiang-ping, ZOU Zhen-long
Chin. Phys. Lett. 1997, 14 (2): 155-157 .  
Abstract   PDF(pc) (201KB) ( 393 )
The signature of the self-microlensing in compact binaries (white dwarfs, neutron stars and black holes) is a flare with the characteristic time of typically a few minutes. The probability of detecting these microlensing events can be as high as 1/50 for a photometric accuracy of Δm = 0.01 in magnitude. The discovery of the self-microlensing by binaries would furnish an additional way to find the masses of the lens and the companion, and will be promising for the searches of black holes.
Dyon Solution in Axis Symmetric Spacetime
SHEN You-gen, CHENG Zong-yi
Chin. Phys. Lett. 1997, 14 (2): 158-160 .  
Abstract   PDF(pc) (137KB) ( 343 )
By utilizing the method of complex extension in this paper, the rotative axis symmetric solution in the Einstein-Maxwell-conformal scalar field theory is obtained. This solution contains four parameters: scalar charge, electric charge, magnetic charge and the one related with spherical rotation, and it is not a black hole solution.
23 articles