共查询到20条相似文献,搜索用时 15 毫秒
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V. B. Shikin 《JETP Letters》2006,84(1):27-30
A breakdown mechanism is discussed for the current-voltage characteristic of the system of integer Hall channels in a 2D sample with a regularly inhomogeneous 2D electron density. It has been shown that the appearance of an external potential V on the “edges” of such strips leads to two alternatives: as V increases, the strip width decreases to zero or increases geometrically but “deteriorates qualitatively.” In both cases with their (different) thresholds, integer strips lose their properties inherent in them in the quantum Hall effect regime. These thresholds are attributed here to the asymmetric breakdown of the quantum Hall effect for the system of integer channels. 相似文献
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Recent low-temperature scanning-force-microscopy experiments on narrow Hall bars, under the conditions of the integer quantum Hall effect (IQHE) and its breakdown, have revealed an interesting position dependence of the Hall potential, which changes drastically with the applied magnetic field and the strength of the imposed current through the sample. The present paper shows, that inclusion of Joule heating into an existing self-consistent theory of screening and magneto-transport, which assumes translation invariant Hall bars with a homogeneous background charge due to doping, can explain the experimental results on the breakdown of the IQHE in the so called edge-dominated regime. 相似文献
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We have studied the channel-size dependence of nonequilibrium electrons excited into higher Landau levels in a quantum Hall conductor, by mapping cyclotron emission in Hall bars of different sizes. The images obtained reveal that the spatial evolution of the nonequilibrium electrons with current density significantly depends on the channel width of the Hall bar on a macroscopic scale of several hundred microms. This observation provides clear evidence of a macroscopic channel-size effect, which can be reasonably understood as originating from a very long equilibrium length of the excited electrons. 相似文献
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J. E. Avron 《Journal of Geometry and Physics》1984,1(3):13-23
We consider a particle in a 2 dimensional plane in a periodic potential and a homogeneous magnetic field perpendicular to the plane. Kubo's expression for conductivity of the Hall current is an integer.
This result of Thouless, Kohomoto, Nightingale and den Nijs is interpreted geometrically. 相似文献
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Schakel AM 《Physical review D: Particles and fields》1991,43(4):1428-1431
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M. V. Budantsev A. G. Pogosov A. E. Plotnikov A. K. Bakarov A. I. Toropov J. C. Portal 《JETP Letters》2009,89(1):46-49
We have compared the properties of the nonequilibrium state of the two-dimensional electron gas observed in the samples of different types by means of magnetotransport and magnetization measurements in the quantum Hall effect regime at integer filling factors n. It has been found that the range of filling factors corresponding to the nonequilibrium state is universal for the samples of different types and different measurement techniques and varies from 0.1 to 0.3 for n changing from 1 to 4. The comparison indicates that the observed nonequilibrium state is not directly caused by the appearance of eddy currents and the dielectric phase in the two-dimensional electron gas but is probably associated with the magnetic field-induced phase transition. 相似文献
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Magnetotransport measurements in a clean two-dimensional electron system confined to a wide GaAs quantum well reveal that, when the electrons occupy two electric subbands, the sequences of fractional quantum Hall states observed at high fillings (ν>2) are distinctly different from those of a single-subband system. Notably, when the Fermi energy lies in the ground state Landau level of either of the subbands, no quantum Hall states are seen at the even-denominator ν=5/2 and 7/2 fillings; instead, the observed states are at ν=[i+p/(2p±1)], where i=2, 3, 4 and p=1, 2, 3, and include several new states at ν=13/5, 17/5, 18/5, 25/7, and 14/3. 相似文献
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Jingbo Xia 《Communications in Mathematical Physics》1988,119(1):29-50
We study the two-dimensional Hall effect with a random potential. The Hall conductivity is identified as a geometric invariant associated with an algebra of observables. Using the pairing betweenK-theory and cyclic cohomology theory, we identify this geometric invariant with a topological index, thereby giving the Hall conductivity a new interpretation.Supported in part by the National Science Foundation under Grant No. DMS-8717185 相似文献
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The quantum spin Hall (QSH) state of matter is usually considered to be protected by time-reversal (TR) symmetry. We investigate the fate of the QSH effect in the presence of the Rashba spin-orbit coupling and an exchange field, which break both inversion and TR symmetries. It is found that the QSH state characterized by nonzero spin Chern numbers C(±) = ±1 persists when the TR symmetry is broken. A topological phase transition from the TR-symmetry-broken QSH phase to a quantum anomalous Hall phase occurs at a critical exchange field, where the bulk band gap just closes. It is also shown that the transition from the TR-symmetry-broken QSH phase to an ordinary insulator state cannot happen without closing the band gap. 相似文献
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