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991.
We present an experimental study of low temperature electronic transport in the hybridization gap of inverted InAs/GaSb composite quantum wells. An electrostatic gate is used to push the Fermi level into the gap regime, where the conductance as a function of sample length and width is measured. Our analysis shows strong evidence for the existence of helical edge modes proposed by Liu et al [Phys. Rev. Lett. 100, 236601 (2008)]. Edge modes persist in spite of sizable bulk conduction and show only a weak magnetic field dependence-a direct consequence of a gap opening away from the zone center. 相似文献
992.
利用理论分析和数值计算的方法,研究了偏置磁极周期会切磁铁产生的、可用于带状电子束宽边聚焦的边聚焦场。结果表明:增加偏置长度,减小电子束通道宽度,增大磁极轴向长度可以在基本不改变边聚焦场在x方向上分布特性的前提下提高幅值;增大电子束通道的高度,增大磁极厚度均可以减小边聚焦场在x方向上分布曲线的曲率,但同时其幅值也会降低,该降低可利用前述方法予以补偿。在对带状电子束宽边聚焦进行束匹配时,可以先进行曲率匹配,再进行幅值匹配。在进行参数选择时,应合理选择束通道高度和磁极厚度的取值,以避免束通道内的边聚焦场在x方向上的分布出现曲率反向。 相似文献
993.
Broadband water window supercontinuum generation with a w +3w/2 multicycle two-colour pulse 下载免费PDF全文
We propose a method to generate a high-efficiency broadband water window supercontinuum with a w + 3w/2 multicycle two-colour pulse. Our results reveal that the 3w/2 laser pulse can simultaneously modulate the acceleration step and the ionization step, which not only broadens the bandwidth but also enhances the yield of the generated supercontinuum. An ultra-broadband supercontinuum from 290 eV to 555 eV covering the whole water window is generated. Using this method, we expect that an isolated 62-as pulse with a minor pre-pulse can be directly obtained. 相似文献
994.
X. X. Jin J. G. Du G. Jiang X. Luo X. W. Wang 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2011,64(2-3):323-329
Using density functional theory (DFT) with valence basis set LANL2TZ to study the relative stabilities and electronic properties of the most stable structures of Nb n V(0,?±1) (n = 1?6) clusters. The ground state structures of Nb n V (0,?±1) keep the similar geometric structure as the host Nb n clusters. The doping of vanadium atom enhances the chemical activities of Nb n clusters. The Nb3V and Nb6V are more stable than other clusters. The average binding energy of charged systems (Nb n V+ and Nb n V? clusters) are generally larger than neutral Nb n V clusters natural population analysis shows that there are charge transfers from niobium to vanadium atoms in the small Nb1?4V, however, for larger clusters (Nb5V and Nb6V), the charge transfers are from vanadium to niobium atoms. The vertical and adiabatic ionization potentials (VIP and AIP) are estimated and the vertical one is more close to experimental results. 相似文献
995.
(Na0.5K0.5)0.975Li0.025Nb0.82−xSbxTa0.18O3 lead-free piezoceramics were prepared by the conventional solid-state sintering method. All samples possess a pure perovskite phase, and no secondary phase could be certified. The crystal structure changes from tetragonal to pseudo-cubic with increasing amount of Sb. The ferroelectric Curie temperature (Tc) shifts to lower temperature while the tetragonal to orthorhombic phase transition temperature (To-t) shows no obvious change with increasing Sb5+. Enhanced piezoelectric and electromechanical properties are obtained with x=0.06: d33=352 pC/N, kp=47% and kt=38%, showing that they could be promising candidates as lead-free piezoelectric materials. 相似文献
996.
D. Cao Q. Peng S. Du J. Xu Y. Guo J. Yang Y. Bo J. Zhang D. Cui Z. Xu 《Applied physics. B, Lasers and optics》2011,103(1):83-88
A water-cooled 785 nm diode-side-pumped high-power CW Tm:YAG laser system at 2 μm is reported. 200 W output power is achieved
with cooling water running at 8°C. As far as we know, this is the highest output power for a diode-pumped all solid-state
2 μm Tm:YAG laser. The output corresponds to optical-to-optical conversion efficiency of 11.2%, with a slope efficiency of
about 22.8%. To make the system structure simple, only deionized water is used as the coolant instead of alcohol- or glycol-water
mixture or the liquid nitrogen in the reported high-power Tm rod laser experiments, which were performed at low temperature
near the freezing point of water, or even below. 相似文献
997.
Peng Zhou Hongliang Ma Yingying Du Yongmei Han Bo Lu Minjian Zhong 《Applied Physics A: Materials Science & Processing》2011,102(2):295-299
Crystalline TiO2 was induced three dimensionally inside Bi-free glass sample by an 800 nm, 250-kHz femtosecond laser irradiation. Micro-Raman
spectra analysis indicated that the laser-induced crystals in the focal point of the laser beam were monophase TiO2 rutile. Continuous crystalline lines were written through moving the focal point of the laser beam inside the glass. The
results demonstrate that this technique is a convenient method to engrave three-dimensional patterns of crystals for fabricating
integrated optical devices in transparent materials. 相似文献
998.
复分散系相函数在辐射介质传热中是关键参数,蒙特卡洛法兼具数值算法与试验测量的优点.利用该方法计算复分散系的多重散射相函数克服了以往算法的缺点,可以体现多重散射的影响,并且可以计算任意形状控制体的相函数.大量的数学实验发现当介质系密度增大时,散射能量在4π空间内分布趋于均匀. 相似文献
999.
在NaSh模型的基础上,考虑交通事故和养护路段等意外事件对高速公路交通流的影响,建立了有意外事件影响的在车道管制下的高速公路交通流元胞自动机模型,并进行数值模拟. 研究发现:意外事件对高速公路交通流有明显影响,并且意外事件对交通流的影响在某一密度值范围内尤其明显,且意外事件堵塞点在第一车道比在第二车道对交通流的影响小;同时,在该密度值范围内,意外事件堵塞时间和堵塞路段长度越长,对交通流的影响就越大.
关键词:
元胞自动机
交通流
意外事件 相似文献
1000.
提出了一种考虑绝缘栅极双极晶体管(insulated gate bipolar transistor,IGBT) 基区载流子不同注入条件的物理模型. 在小注入和大注入情况下,分别建立描述IGBT基区载流子运动的输运方程(ambipolar transport equation,ATE),并确定边界条件. 采用傅里叶级数法求解载流子输运方程,并将计算结果分别与IGBT手册提供的实验数据和Hefner模型计算结果相比较,验证了本文提出物理模型的正确性.
关键词:
绝缘栅极双极晶体管
物理模型
注入条件
双极输运方程 相似文献