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131.
L.A. Farina X. Bai . Kurdak S. Chakrabarti P. Bhattacharya M.Shayegan 《Physica E: Low-dimensional Systems and Nanostructures》2006,34(1-2):187
We have fabricated devices on GaAs/AlGaAs heterostructures, containing two-dimensional electron gases, that consist of three point contacts surrounding an etched antidot with an Al/AlOx/Al single electron transistor. The single electron transistor measurement shows rearrangement of neighboring charged impurities with a characteristic stability time scale of 20 s in one device and greater than 1 h in a second device. We also measured the resistance of the point contact–antidot constriction versus magnetic field. In a device with a 20 s stability time, we see a high noise level and poor reproducibility. In a device with a long stability time, much greater than 1 h, we are able to see reproducible features including Aharonov–Bohm oscillations. 相似文献
132.
T. Aoyama N. Maeda 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,54(2):157-168
The induced Chern-Simons term for a paired electron state is calculated in the
quantum Hall system by using a field theory on the von Neumann lattice.
The coefficient of the Chern-Simons term, which is the Hall conductance,
has not only the usual term proportional to a filling factor due to
P (parity) & T (time reversal) symmetry breaking
but also correction terms due to P & T & U(1) symmetry breaking.
The correction term essentially comes from the Nambu-Goldstone
mode and depends on an infrared limit.
It is shown that the correction term is related to a topological number of a gap function
in the momentum space. 相似文献
133.
This paper generalizes the analysis of four magnetohydrodynamic (MHD) flow problems of an Oldroyd-B fluid discussed by Asghar
et al. [Int. J. Non-linear Mech. 40, 589–601 (2005)] into three directions: (i) to discuss the problems in a porous medium using modified Darcy’s law (ii) to
see the influence of Hall current (iii) to determine the effect of rheological parameter of Burgers’ fluid. Analytical solutions
of velocity distribution valid at large and small times are given in each problem. Comparison has been provided for Oldroyd-B
and Burgers’ fluids through graphs. The physical interpretation is also included. 相似文献
134.
本文定义了管范畴上的一些算子,研究了它们的一些性质,给出了循环单列代数的Ringel-Hall代数H(T)的结构常数FML,N的一个计算公式.利用这些算子和这个公式,我们得到了其合成代数C(T)及半单模[l(?)i=1nSi](t∈Z+)在H(T)中的一些中心化子.事实上,它们是H(T)的中心元素,且是H(T)在其合成代数C(T)上代数无关的生成元. 相似文献
135.
近来,关于无序涡旋物质凝聚体的著名的涡旋玻璃理论受到了来自某些新实验的严重质疑.我们重新审查了高温超导体的临界标度,发现超导混合态的直流伏安特性具有扩展幂律的一般形式.由该扩展幂律型非线性方程模拟的等温线和Strachan等人得到的实验数据[Phys.Rev.Lett.87(2001),067007]符合得很好.文中还讨论了长期以来围绕纵向电阻率和霍尔电阻率的临界指数的某些争议. 相似文献
136.
细电子束Cockcroft–Walton加速器的研究 总被引:2,自引:0,他引:2
细电子束由加速器通过电子枪发射电子,经电子透镜及偏转射向目标靶.以SDS-3电子束曝光机为基础,完成了电子束Cockcroft-Walton加速器噪声抑制的最优状态实验.系统为加速器调整电路提供一个正比于输入电压的电流.补偿放大器是由一个主放大器和一个辅助放大器组成,辅助放大器消除了主放大器自身的失调漂移.文中介绍了复合调整式Cockcroft-Walton加速器的总体设计方案,给出了实现加速器高稳定度的关键技术措施.从加速器总输出中滤去噪声信号,获得稳定的输出电压,并使电子束曝光机刻蚀出的图形质量和线条分辨率都得到了提高 相似文献
137.
We study the partition function for the low-energy edge excitations of the incompressible electron fluid. On an annular geometry, these excitations have opposite chiralities on the two edges; thus, the partition function takes the standard form of rational conformal field theories. In particular, it is invariant under modular transformations of the toroidal geometry made by the angular variable and the compact Euclidean time. The Jain series of plateaus have been described by two types of edge theories: the minimal models of the W1+∞ algebra of quantum area-preserving diffeomorphisms, and their non-minimal version, the theories with
affine algebra. We find modular invariant partition functions for the latter models. Moreover, we relate the Wen topological order to the modular transformations and the Verlinde fusion algebra. We find new, non-diagonal modular invariants which describe edge theories with extended symmetry algebra; their Hall conductivities match the experimental values beyond the Jain series. 相似文献
138.
Yu.B. Vasilyev C. Stellmach G. Nachtwei R.A. Suris S.D. Suchalkin B.Ya. Meltser S.V. Ivanov P.S. Kopev 《Physica E: Low-dimensional Systems and Nanostructures》2006,34(1-2):308
In tilted magnetic fields a bilayer electron–hole system is found to generate a photocurrent under terahertz radiation as the system is tuned to electron cyclotron resonance conditions. The photoinduced current amplitude oscillates with the magnetic field in correlation with Shubnikov–de Haas oscillations for electrons. The phenomenon is accounted for by a photomagnetic effect in electron–hole systems in the quantum Hall regime and has potentialities for terahertz detection and spectroscopy. 相似文献
139.
140.