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Band structure, Fermi surface, and superconducting
gap in FeAs-based superconductors revealed by angle-resolved photoemission
spectroscopy
Xing-jiang ZHOU (周兴江), Guo-dong
LIU (刘国东), Hai-yun
LIU (刘海云), Lin
ZHAO (赵林), Wen-tao
ZHANG (张文涛), Xiao-wen
JIA (贾小文), Jian-qiao
MENG (孟建桥),
Front. Phys. . 2009, 4 (4 ): 427-432.
https://doi.org/10.1007/s11467-009-0058-y
In this paper, we present a brief review on our angle-resolved photoemission measurements on the band structure, Fermi surface, and superconducting gap of the newly-discovered FeAs-based high temperature superconductors. (1) The Fermi surface of the FeAs-based compounds are characterized by the hole-like Fermi surface sheets near Γ (0, 0) and the existence of singular Fermi spots near M (π ,
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Magneto-thermopower of parent compound LaFeAsO
Zeng-wei ZHU(朱增伟), Qian TAO(陶前), Yu-ke LI(李玉科), Mi HE(何咪), Guang-han CAO(曹光旱), Zhu-an
XU(许祝安),
Front. Phys. . 2009, 4 (4 ): 455-458.
https://doi.org/10.1007/s11467-009-0015-9
We report the effect of magnetic field on the transport properties of polycrystalline parent compound LaFeAsO. The magnetic field has no significant influence on the structural phase transitions or spin density wave (SDW) ordering of small moments on iron, but causes large positive magento-resistance below 100K. Meanwhile, the absolute magnitude of thermopower, which is negative, increases remarkably with increasing magnetic field below 100K. Such a large positive magneto-thermopower was first reported in this iron arsenide. The result suggests that there could exist an enhancement of SDW gapping in holelike Fermi surface.
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Studies on the superconductivity for the “111”
type iron arsenide superconductor
Xian-cheng WANG (望贤成), Qing-qing
LIU (刘清青), Liu-xiang
YANG (杨留响), Zheng
DENG (邓正), Yu-xi
LÜ (吕玉玺), Wei-bo
GAO (高伟波), Si-jia
ZHANG (张思佳), Ri-cheng
YU (禹日成), Chang-qing JIN (靳常青),
Front. Phys. . 2009, 4 (4 ): 464-468.
https://doi.org/10.1007/s11467-009-0042-6
The “111” type LixFeAs (x ranges from 0.8 to 1.2) with Cu2 Sb type tetragonal structure was synthesized with T c 18K. The isostructure NaFeAs was further studied, which shows superconductivity with T c up to 26K. The effect of pressure on superconductivity was investigated.
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Advances in surface plasmon resonance-based high
throughput biochips
San-jun ZHANG(张三军), Lotfi BERGUIGA, Nicolas HUGO, Thibault ROLAND, Francoise ARGOUL, Juan ELEZGARAY, Wen-xue
LI(李文雪), He-ping ZENG(曾和平)
Front. Phys. . 2009, 4 (4 ): 469-480.
https://doi.org/10.1007/s11467-009-0069-8
This article reviews our recent advances in surface plasmon resonance (SPR) based biochips. It includes four issues, which are the preparation and characterization of high quality gold film, the preparation and characterization of self-assembled monolayer (SAM), dynamics of DNA adsorption on SAMs, and SPRbased microscopies. Numerous topics related to SPR, such as, the modeling of SPR by transmission matrix, effective medium theory, applications of SPR in biology, and SPR-based novel microscopies, are discussed. A novel electrochemical technique, which is extremely useful for the preparation and characterization of high quality SAMs, is also discussed.
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One-dimensional self-assembly of inorganic nanoparticles
Tao HU(胡涛), Yan GAO(高燕), Zhi-yong TANG(唐智勇), Zhen-long WANG(王振龙)
Front. Phys. . 2009, 4 (4 ): 487-496.
https://doi.org/10.1007/s11467-009-0066-y
This review is focused on the recent research progresses on one-dimensional (1-D) inorganic nanoparticle (NP) assemblies. First, we introduce some preparation methods of 1-D NP assemblies, which are the base of the investigation to 1-D NP assemblies. In the following part, we discuss the formation mechanism of 1-D NP assemblies, which is very important for us to understand the self-assembly process. We also summarize the novel properties of 1-D NP assemblies. Finally, we outlook the development of 1-D NP assemblies in the near future. We believe that the scientific and technical potentials of NP assemblies are immense, and their future is bright.
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Diffractive upsilon photo-production off the
proton in the QCD inspired model
Ji-huan PAN (潘继环), Li-juan
ZHOU (周丽娟), Wei-xing MA (马维兴),
Front. Phys. . 2009, 4 (4 ): 534-548.
https://doi.org/10.1007/s11467-009-0061-3
Based on the generalized vector meson dominance model in QCD, we study the photoproduction of vector meson Υ off the proton by use of the QCD-inspired model in which the contributions from quark–quark, gluon–gluon and quark–gluon interference term to observable are taken into consideration. Calculations are performed for total cross section σ tot , differential cross section dσ /dt , ratio of the real part to imaginary part of forward scattering amplitude ρ and nuclear slop parameter function β . We analyze the individual contributions from quark gluon degrees of freedom and the QCD Odderon to the total cross section σ tot (s), differential cross section dσ /dt , ratio of the real part to imaginary part of the forward scattering amplitude ρ , and nuclear slop parameter function β . The mediators of interactions between projectiles (the quark and antiquark pair fluctuated from the real photon) and the proton target (three quark system) are the tensor Glueball and Odderon instead of using the usual Pomeron exchange. The theoretical predictions for σ tot (s ) are consistent with the experimental data within error bars of the data. The data for dσ /dt , β and ρ are urgently needed. The gluon–gluon interaction makes a significant contribution to the observables while the Odderon contribution is negligibly small. Therefore, we may conclude that it is impossible to find the QCD Odderon in the γ+p →Υ+p process as suggested before.
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Modeling mobile ad hoc communication networks
on two-dimensional square lattice
Li WANG (王黎), Zhi-ming GU (古志鸣), Chen-ping ZHU (朱陈平), Xi-tao LI (李曦涛),
Front. Phys. . 2009, 4 (4 ): 556-560.
https://doi.org/10.1007/s11467-009-0074-y
In this paper, we model the mobile ad hoc communication network on a two-dimensional square lattice. Both structure and function of it depend on transmission range and site-occupancy of nodes. Critical occupancies σ c for different transmission ranges r to maintain global connection are found. Universal scaling function behaves as η~f (R β σ ), where R =(r −r 0 )/r 0 , and the scaling exponent β =−0.61, which distinguishes itself from percolation in previous lattice or network models. When the occupancy σ is near the threshold σ c , individual nodes self-organize into a dynamic small world network relative to geometric distance. The network has a cut-off degree below which clustering coefficient keeps constant, which distinguish itself from other systems and has its potential application in technical designs.
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18 articles