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Volume 4 Issue 6
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Original Articles
EFFECT OF ION BEAM MIXING/IMPLANTATION AT LOW TEMPERATURE ON SUPERCONDUCTIVITY IN PALLADIUM-HYDROGEN AND PALLADIUM-COPPER-HYDROGEN SYSTEMS
LI Hongcheng, DONG Ziwen, YANG Feng, WANG Ruilan, LIU Jiarui, Guan Weiyan
Chin. Phys. Lett. 1987, 4 (6): 241-244 .  
Abstract   PDF(pc) (55KB) ( 364 )
The highest superconducting transition temperature of 8.42 and 5.16K has been observed in the alloy system PdH and PdCuH, where the atomic ratio n=H/Pd(Cu) are 1 and 0.6, respectively. The effect of lattice disorder induced by 220keV Ar ion beam bombardment at liquid helium-temperature is detrimental to the superconductivity.
OBSERVATION OF CORRELATION BETWEEN ANGULAR DISTRIBUTION AND DOPPLER BROADENING OF POSITRON ANNIHILATION
JIANG Huilin, TANG Xiaowei*
Chin. Phys. Lett. 1987, 4 (6): 245-248 .  
Abstract   PDF(pc) (47KB) ( 481 )
Using a new technique we have observed the correlation between the angular distribution and Doppler broadening of the positron annihilation in silica aerogel and synthetic quartz crystal, for which the relative intensities of the central peaks of the angular correlation with fine selection of gamma ray energy are 1.7 and 1.4 times those without energy selection, respectively.
DEPTH PROFILING OF HYDROGEN IN SOLIDS BY ELASTIC RECOIL DETECTION WITH 19F IONS
LIU Jiarui, ZHU Peiran, FENG Aiguo, LI Dawan*
Chin. Phys. Lett. 1987, 4 (6): 249-252 .  
Abstract   PDF(pc) (56KB) ( 410 )
The hydrogen depth profiling in solids has been done by elastic recoil detection (ERD) technique with multicharged 19F ion beam from a small Tandem Accelerator of 2x1.7MV. Details of the experimental technique are described. The depth resolution of about 230Å in the near-surface regions (~5000Å)is much better than that of ERD technique with 2.5MeV He beam and heavy ion beam of 30MeV.
THE DEEP LEVELS IN GaSb/AlSb(00l) SUPERLATTICES
HUANG Mingzhu, GU Yiming, REN Shangyuan
Chin. Phys. Lett. 1987, 4 (6): 253-256 .  
Abstract   PDF(pc) (51KB) ( 406 )
The electronic states, especially the deep levels of the defects in GaSb/AlSb (001) superlattices have been calculated. The band gap becomes larger and the donor binding energy becomes deeper with the decrease of the quantum well width. The impurity deep levels exhibit a position dependent relation.
A NEW SOLUTION TO THE ANDERSON MODEL AND THE WILSON RATIO OF THE HEAVYFERMION SYSTEM
FENG Shiping
Chin. Phys. Lett. 1987, 4 (6): 257-260 .  
Abstract   PDF(pc) (40KB) ( 449 )
The solution of Anderson model is got by using the Bogoliubov-type transformation. The calculated Wilson ratio for the heavy-fermion systems is in qualitative agreement with the experimental results.
HIGH PRESSURE STUDY OF GaAs-AlXGa1-XAs MULTIPLE QUANTUM WELL STRUCTURE
ZHAO XueShu, LI Guohua, HAN Hexiang, WANG Zhaoping, TANG Ruming*, WANG Lijun*
Chin. Phys. Lett. 1987, 4 (6): 261-264 .  
Abstract   PDF(pc) (52KB) ( 615 )
The pressure coefficients between Γ conduction subbands, heavy( h) and light (1) hole subbands are determined. It is found that the pressure coefficient decrease with increasing subband energy or decreasing well width(Lz), from 10.3meV/kbar for the 130Å well to 9.6meV/kbar for the 29Å well. This result shows that the Γ valley of GaAs is not a rigid sphere with same pressure coefficient. Pressure dependence of photoluminescence intensity has been also measured for both the 130Å and 29Å wells. It is markedly different from that of the bulk GaAs.

QUANTUM-GRAVITY INTERPRETATION OF BRANS-DICKE THEORY---THE BACK-REACTION OF THE VACUUM MATTER FIELD UPON THE EINSTEIN SPACE-TIME
LIU Liao, HUANG Chaoguang*
Chin. Phys. Lett. 1987, 4 (6): 265-268 .  
Abstract   PDF(pc) (39KB) ( 454 )
A quantum gravity version is given to the Brans-Dicke theory. We find that the matter field quantum fluctuation induces the conformal quantum fluctuation of space-time, and that the latter backreacts to the classical space-time and transforms it from Einstein space-time into the Brans-Dicke one.
LANDAUS FERMI LIQUID THEORY OF HEAVY-FERMION SUPERCONDUCTING SYSTEMS
FENG Shiping
Chin. Phys. Lett. 1987, 4 (6): 269-272 .  
Abstract   PDF(pc) (38KB) ( 420 )
We have established a relation between the parameters of periodic Anderson model Hamiltonian and the Landau's phenomenological paramerters, and applied it to heavy-fermion superconducting systems. The calculated results of specific heat coefficients and superconducting critical temperatures are in agreement with the experimental ones. The conclusion is that heavy-fermion superconducting systems induced by Fermi liquid interaction are P-wave type.

QUANTUM AND NON-MARKOVIAN EFFECTS IN BROWNIAN MOTION
WU Xizhen, LI Zhuxia, ZHUO Yizhong
Chin. Phys. Lett. 1987, 4 (6): 273-276 .  
Abstract   PDF(pc) (50KB) ( 344 )
The analytical expressions of the second moments for a dissipative quantum system are derived by using path integral method with a solvable model. The quantum and non-Markovian effects on the quantum Brownian motion are studied quantitatively.
CARBON-ION RADIOACTIVITY OF 223Ra
LU Xiting, WANG Xiangyun, JIANG Dongxing, LIU Guoxing*, LIANG Guozhao*
Chin. Phys. Lett. 1987, 4 (6): 277-279 .  
Abstract   PDF(pc) (39KB) ( 721 )
The carbon-ion radioactivity of 223Ra has been measured with solid state track detectors. A branching ratio of the emission of 14c nuclei to that of alpha-particles of (8.7±1.7)x10-10 is obtained. The preformation probability of 14c in 223Ra and the odd-even effect are discussed.
SUPERCONDUCTIVITY AT 89K OF Ba-Y-Cu-O THIN FILMS
ZHAO Bairu, WANG Huisheng, LU Yong, SHI Yinhuan, HUANG Xicheng, ZHAO Yuying, LI Lin
Chin. Phys. Lett. 1987, 4 (6): 280-282 .  
Abstract   PDF(pc) (42KB) ( 447 )
High Tc Ba-Y-Cu-O thin films have been successfully prepared by the RF magnetron sputtering method. The highest Tc onset is determined to be 89.5K and the Tc midpoint is about 55K. Inductive measurement showed that the samples are diamagnetic and the Meissner effect appeared around 10K.
PHOTOREFLECTANCE OF TWO-DIMENSIONAL ELECTRON GAS IN THE SELECTIVELY DOPED GaAS /AlXGa1-XAs HETEROSTRUCTURE GROWN BY MOLECULAR BEAM EPITAXY
TANG Yinsheng, JIANG Desheng*
Chin. Phys. Lett. 1987, 4 (6): 283-285 .  
Abstract   PDF(pc) (39KB) ( 402 )
Room temperature photoreflectance were made on a selectively doped GaAs/n-AlXGa1-XAs two-dimensional electron gas grown by molecular beam epitaxy (MBE). The lineshapes can be made fit by Aspnes' theory, and the results explained with a simple model.
ZERO RESISTANCE AT 91.5K IN THE BA-Y-CU-O COMPOUND SYSTEM
ZHAO Bairu, SHI Yinhuan, Lu Yong, WANG Huisheng, ZHAO Yuying, LI Lin
Chin. Phys. Lett. 1987, 4 (6): 286-288 .  
Abstract   PDF(pc) (36KB) ( 398 )
The oxide compounds of BaxY1-xCuO3-y(x=0.3-0.5) have been successfully prepared. The zero resistance temperature of the samples is at 91.5K. with Tc onesets higher than 100K. The ac magnetic susceptibility measurements show that the superconducting phase at 82K is not less than 85% in volume.
13 articles