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Carbon nanotube transistors with graphene oxide films as gate dielectrics

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Science China(physics,Mechanics & Astronomy) 2010年第5期53卷 828-833页

作者： FU WangYang,LIU Lei,WANG WenLong,WU MuHong,XU Zhi,BAI XueDong & WANG EnGe beijing national {2. for condensed matter physics,institute of physics,chinese academy of sciences,beijing 100190,China beijing national {2. for condensed matter physics Institute of Physics Chinese Academy of Sciences Beijing China

Carbon nanomaterials,including the one-dimensional(1-D) carbon nanotube(CNT) and two-dimensional(2.D) graphene,are heralded as ideal candidates for next generation *** essential component for the development of advanced nanoelectronics devices is processing-compatible ***,in analogy to the widespread use of silicon dioxide(SiO2. in silicon microelectronic industry,we report the proof-of-principle use of graphite oxide(GO) as a gate dielectrics for CNT field-effect transistor(FET) via a fast and simple solution-based processing in the ambient *** exceptional transistor characteristics,including low operation voltage(2.V),high carrier mobility(950 cm2.V-1 s-1),and the negligible gate hysteresis,suggest a potential route to the future all-carbon nanoelectronics.

关键词： carbon-based nanoelectronics graphene oxide gate dielectrics

Interference pattern generation and simulation in the single beam of a white light continuum

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Science China(physics,Mechanics & Astronomy) 2010年第6期53卷 1060-1064页

作者： YU ZhiHao & WENG YuXiang laboratory of Soft matter {2.,institute of {2.,chinese academy of sciences,and national laboratory of condensed matter {2.,beijing 100190,China laboratory of Soft matter {2. Institute of Physics Chinese Academy of Sciences and National Laboratory of Condensed Matter Physics Beijing China

We demonstrate the interference phenomenon in the White Light Continuum(WLC) generated by a single femtosecond laser beam. Different kinds of spatial interference patterns of the WLC generation under various conditions were investigated. The spatial patterns were attributed to interference between the filaments in the WLC generated by the fundamental laser beam yielding the diffraction effect from spatial confinement. Simulations of different patterns were performed. By comparing the results of simulation with those of experiments,the distances of several micrometers between the neighboring filaments can be derived,which agree with the literature values from direct measurements.

关键词： interference supercontinuum generation ultrafast nonlinear optics

An Explicit Function Expression for dc Bias and Temperature Dependence of Magnetoresistances in Magnetic Tunnel Junctions

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Journal of Materials Science & Technology 2002年第6期18卷 497-501页

作者： Xiufeng HANState Key laboratory of Magnetism, institute of physics and Center of {2. matter physics, chinese academy of sciences, beijing 1.0080, China chinese Acad Sci Inst Phys State Key Lab Magnetism Beijing 100080 Peoples R China chinese Acad Sci Ctr Condensed Matter Phys Beijing 100080 Peoples R China

An explicit function expression for the bias voltage or/and temperature dependences of tunnel magnetoresistance ratio and resistances were obtained with a unique set of intrinsic parameters. Two of these intrinsic parameters are the Curie temperature TC and the density of state (DOS) for itinerant majority and minority electrons ξ(ρM/ρm), which are the eigen parameters of ferromagnetic electrodes. Others are the spin-dependent matrix-element ratio (i.e., |Td|2.|TJ|2.) and the anisotropic-wavelength-cutoff energy ECγ of spin-wave spectrum in magnetic tunnel junction (MTJ), which are the structure parameters of an MTJ. These intrinsic parameters can be predetermined using the experimental measurement or, in principle, using the first-principle calculation method for an MTJ with the three key layers of FM/I/FM. Furthermore, a series of experimental data for an MTJ, for example, a spin-valve-type MTJ of Ta (5 nm)/Ni79Fe2.(2. nm)/lr2.Mn78(12.nm)/Co75Fe2.(4 nm)/AI(0.8 nm)-oxide/Co75Fe2.(4 nm)/Ni79Fe2.(2. nm)/Ta (5 nm) in this work, can be self-consistently evaluated and explained using such concise explicit function formulations.

关键词： Magnetic tunnel junction TMR Spin-electron transport Magnon excitation Spin-polarization Magnetotransport

High resistance modulation by the electric field based on La_(0.9)Sr_(0.1)MnO_3/SrTiO_3/Si structure

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Science China(physics,Mechanics & Astronomy) 2009年第9期52卷 1299-1301页

作者： YANG Fang, HE Meng, WEN Juan, JIN KuiJuan, LU HuiBin & YANG GuoZhen beijing national {2. for condensed matter physics, institute of physics, chinese academy of sciences, beijing 100190, China beijing national {2. for condensed matter physics Institute of Physics Chinese Academy of Sciences Beijing China

A field-effect configuration based on La0.9Sr0.1MnO3/SrTiO3/Si structure is fabricated on Si substrate by laser molecular-beam epitaxy. The resistance modulation by electric field of the La0.9Sr0.1MnO3/SrTiO3/Si structure is investigated in detail. An evident resistance modulation effect is observed at 80 K. The channel resistance modulation by field effect reaches 1.4×107% and 2.6×106% when VDS are -2.and -6.5 V, respectively. The ON/OFF ratio of approximately 4000 is obtained. The present results are worthy of further investigations for potential applications of resistance modulation by electrostatic field in the heterostructures consisting of perovskite oxides and Si.

关键词： field effect perovskite oxide thin films resistance modulation

Recent progress in single chip white light-emitting diodes with the InGaN underlying layer

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Science China(physics,Mechanics & Astronomy) 2010年第3期53卷 445-448页

作者： WANG XiaoLi, WANG XiaoHui, JIA HaiQiang, XING ZhiGang & CHEN Hong beijing national {2. of condensed matter, institute of physics, chinese academy of sciences, beijing 1.0080, China beijing national {2. of condensed matter Institute of Physics Chinese Academy of Sciences Beijing China

Tremendous progress has been achieved in white light-emitting diodes (LEDs). To further improve the quality of white light and simplify the fabrication process, a single chip white-light LED with the InGaN underlying layer (UL) was studied and fabricated. The turn-on voltage of this type of LED was 2.7 V, and the spectrum at a forward bias current of 2. mA was comprised of blue (443 nm) and yellow (563 nm) lights. The intensity ratio of blue to yellow light was almost constant with the in- creasing injection current in a certain scope, most important for the solid state illumination. The useful life test showed the light output level remained at a 90% light output level at the driving current of 40 mA after 300 h, meanwhile, the UV and blue LEDs combined with phosphor reached a 2.% value after 144 h within 300 h.

关键词： GaN InGaN white light LED MOCVD

Approaches to improving critical current density of YBCO superconducting thick films deposited by electrophoresis

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Science China(physics,Mechanics & Astronomy) 2004年第2期47卷 165-172页

作者： ZHU Yabin1,2. ZHOU Yueliang2. LIU Zhen2. WANG Shufang2. CHEN Zhenghao2. L?Huibin2. YANG Guozhen2. XIAO Ling3, REN Hongtao3, JIAO Yulei3 & ZHENG Minghui3 1. Department of physics, College of Science, beijing Jiaotong University, beijing 100044, China 2. laboratory of Optical physics, institute of physics and Center for condensed matter physics, chinese academy of sciences, beijing 1.0080, China 3. General Research institute for Nonferrous Metals, beijing 100088, China Correspondence should be addressed to Zhu Yabin (email: ybzhu@***) Department of physics College of Science Beijing Jiaotong University Beijing China laboratory of Optical physics{2. and Center for condensed matter physics Chinese Academy of Sciences Beijing China General Research institute for Nonferrous Metals Beijing China

Fabrication of YBCO superconducting thick films by electrophoresis has been widely reported. However, the value of critical current density (J c) is far from what the practical application requires. The superconducting thick films are obtained using top-seeded melt growth method with different proportional Y2.aCuO5 (Y2.1) addition. High-pressure oxygen has been used in the annealing process to improve the uniformity of the oxygen content in the superconducting thick films. When 40mol% Y2.1 powder is added to the YBa2.u3O7–5 (Y12.) powder,J c for the superconducting thick film by approaches described above reaches 7.008×103 A/cm2.(77 K, 0 T), which is greater than the value ever reported.

关键词： YBCO thick films, electrophoretic deposition, melt-textured.

Oxygen vacancy induced magnetism in BaTiO_(3-δ) and Nb:BaTiO_(3-δ) thin films

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Science China(physics,Mechanics & Astronomy) 2010年第5期53卷 852-855页

作者： YANG Fang,JIN KuiJuan,LU HuiBin,HE Meng,WANG Cong,WEN Juan & YANG GuoZhen beijing national {2. for condensed matter physics,institute of physics,chinese academy of sciences,beijing 100190,China beijing national {2. for condensed matter physics Institute of Physics Chinese Academy of Sciences Beijing China

The unusual magnetic properties are observed in oxygen deficient BaTiO3-δ(BTO) and Nb:BaTiO3-δ(BNTO) thin films fabricated on SrTiO3 substrates by laser molecular beam *** distinct magnetic hysteresis loops are observed in the oxygen deficient BTO and BNTO thin films in a temperature range of 5 to 300 K,whereas the diamagnetism is observed in both BTO and BNTO annealed at 1 atm of *** dopant Nb only enhances the magnetization in BNTO thin films,but has little effect on the *** magnetism of BTO and BNTO films is proposed to be the oxygen vacancies by origin.

关键词： oxygen vacancy magnetism BaTiO3-δ(BTO) Nb:BaTiO3-δ(BNTO) thin films

Geometry of Broad Line Regions of Active Galactic Nuclei

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chinese Journal of Astronomy and Astrophysics 2008年第1期8卷 50-62页

作者： Xiao-Rong Lü1 Key laboratory for Particle Astrophysics, {2. of High Energy physics, chinese academy of sciences, beijing 100049 2.Graduate School of chinese academy of sciences, beijing 100049 Key laboratory for Particle Astrophysics Institute of High Energy Physics Chinese Academy of Sciences Beijing 100049 Graduate School of chinese academy of sciences Beijing 100049

It has long remained an open question as to the geometry of the broad line region （BLR） in active galactic nuclei （AGNs）. The reverberation mapping technique which measures the response of the broad emission lines to the ionizing continuum, when combined with multiwavelength continuum fitted by sophisticated accretion disks, provides a way of probing the BLR geometry. We analyze a sample of 35 AGNs, which have been monitored by the reverberation mapping campaign. In view of energy budget, the reverberation-based BH masses are found to be in agreement with those obtained by accretion disk models in two thirds of the present sample while the reverberation mapping methods underestimate the BH masses in about one third of objects, as also suggested by CoUin et al. in a recent work. We point out that there are obviously two kinds of BLR geometry, which are strongly dependent on the Eddington ratio, and separated by the value LBol/LEdd - 0.1. These results prefer a scenario of the disk and wind configuration of the BLR and identify the Eddington ratio as the physical driver regulating the wind in the BLR.

关键词： accretion, accretion disks - galaxies active - galaxies Seyfert - quasars general

New quantum tunneling steps in Mn_(11)Cr/Mn_(12. mixed crystal

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Science China(physics,Mechanics & Astronomy) 2010年第9期53卷 1769-1771页

作者： ZHOU YuRong1,LI YanRong1,FAN ZhenJun2.& WANG YunPing1 1beijing national {2. for condensed matter physics,institute of physics,chinese academy of sciences,beijing 100190,China 2.chool of Materials sciences and Technology,China University of Geosciences,beijing 430074,China beijing national {2. for condensed matter physics Institute of Physics Chinese Academy of Sciences Beijing China School of Materials sciences and Technology China University of Geosciences Beijing China

Magnetic properties of Mn11Cr and Mn12.mixed crystal at low temperature are studied.A new set of quantum tunneling steps discovered in magnetization curves suggests that there may exist another kind of single molecula... 详细信息

关键词： quantum tunneling molecular magnet magnetization curve