			Home About us Contact

Quantum Hall Effect (quantum + hall_effect)

Distribution by Scientific Domains

Physics and Astronomy	83%

Selected Abstracts

The absence of an ideal two dimensionality in QHE

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 5 2003
M. Saglam
Abstract The solution of the Schrödinger equation for the Quantum Hall Effect (QHE) system is given for a harmonic impurity potential. It is shown that at a magnetic field B = Bi if there are ,i Landau levels below or just equal to the Fermi level then there will be at least 2,i sublayers of electrons. At the extreme limit, when all the electrons are in the ground state Landau level, there will be at least two sublayers playing a role in the system. [source]

Quantum statistics of charged particles and fingerprints of wigner crystallization in D dimensions

INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 15 2006
N. H. March
Abstract After a brief summary of the physical arguments underlying Wigner's original concept in 1934 of a quantal electron crystal, theoretical interpretation of a number of experimental findings are presented. These include (i) low-density carriers in semiconductors in applied magnetic fields in both three, and recently two, dimensions; and (ii) low-temperature phase diagram of underdoped high Tc cuprates; fullerides with relatively low Tc are also referred to in a related context. Interpretation of areas (i) and (ii) focuses on the relevance of both Fermi,Dirac and anyonic (fractional) statistics, the latter in relation to the proposed melting curve of the two-dimensional (2D) magnetically induced Wigner solid into the Laughlin liquid phase, which is the seat of the fractional quantum Hall effect. A brief discussion follows of crystalline phases additional to the Wigner solid, namely Skyrmion and Hall crystals. Bose,Einstein statistics is then referred to, but now in relation to finite-size confined quantal assemblies, with fingerprints of Wigner molecules the focus. Finally, quasi-1D lattices are considered, both in Bechgaard salts and in the very recent single-electron counting experiment of Bylander et al. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006 [source]

Hartree,Fock interactions in the integer quantum Hall effect

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 2 2008
Rudolf A. Römer
Abstract We report on numerical studies into the interplay of disorder and electron,electron interactions within the integer quantum Hall regime, where the presence of a strong magnetic field and two-dimensional confinement of the electronic system profoundly affects thermodynamic and transport properties. We emphasise the behaviour of the electronic compressibility, the local density of states, and the Kubo conductivity. Our treatment of the electron,electron interactions relies on the Hartree-Fock approximation so as to achieve system sizes comparable to experimental situations. Our results clearly exhibit manifestations of various interaction-mediated features, such as non-linear screening, local charging, and g -factor enhancement, implying the inadequacy of independent-particle models for comparison with experimental results. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Hall conductivity as a topological invariant

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 6 2005
A. Kunold
Abstract The object of the present work is to study the quantum Hall effect through its symmetries and topological aspects. We consider the model of an electron moving in a two-dimensional lattice in the presence of applied in-plain electric field and perpendicular magnetic field. We refer to this as the two dimensional electric,magnetic Bloch problem (EMB). The Hall conductivity quantization beyond the linear response approximation is analyzed. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Persistent photoconductivity in quantum dot layers in InAs/GaAs structures

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 4 2003
V. A. Kulbachinskii
Abstract We synthesized InAs/GaAs structures with quantum dot layers and investigated electron (Si doping) lateral transport in the temperature interval 0.05 K < T < 300 K in the dark and under illumination by light over a wide interval of wavelengths in magnetic fields up to 6 T. All the samples exhibited a positive persistent photoconductivity at T < 250 K. Without illumination in the high carrier density samples the Shubnikov,de Haas effect and the quantum Hall effect were observed. Low carrier density samples showed a 2D Mott variable range hopping conductivity. The morphology of the quantum dot layers was investigated by atomic force microscopy (AFM). The length of localization exceeds the average quantum dot size and correlates very well with the quantum dot cluster size obtained by AFM. [source]

The distinction of integer and fractional Quantum Hall Effect is a mathematical artifact without physical merit

ANNALEN DER PHYSIK, Issue 5 2003
E.J. Post
Abstract Many body wave function assessments of the quantum Hall effect are compared with a global assessment using Aharonov-Bohm and Gauss-Ampère period-integrals as counters of flux and charge quanta. Experiment pleads in favor of a two quanta unified description in terms of flux and charge numbers. [source]