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We report an experimental study of the quantum corrections to the longitudinal conductivity and the Hall coefficient of a low mobility, high density two-dimensional two-dimensional electron gas in a AlGaAs/GaAs/AlGaAs quantum well in a wide…

Mesoscale and Nanoscale Physics · Physics 2015-06-24 Vincent Thomas Francois Renard , O. A. Tkachenko , Ze Don Kvon , E. B. Olshanetsky , A. I. Toropov , J. C Portal

By means of degenerate four-wave mixing (FWM), we investigate the quantum coherence of electron-hole pairs in the presence of a two-dimensional electron gas in modulation-doped GaAs-AlGaAs quantum wells in the quantum Hall effect regime.…

When interacting two-dimensional electrons are placed in a large perpendicular magnetic field, to minimize their energy, they capture an even number of flux quanta and create new particles called composite fermions (CFs). These complex…

Mesoscale and Nanoscale Physics · Physics 2011-03-28 T. Gokmen , Medini Padmanabhan , M. Shayegan

We investigate two-dimensional trilayered quantum systems with multi-orbital conduction bands by focusing on the role played by the layer degree of freedom in setting the character of nodal line semimetals. The layer index can label the…

Mesoscale and Nanoscale Physics · Physics 2019-07-24 F. Forte , D. Guerra , C. Noce , W. Brzezicki , M. Cuoco

In a two-subband GaAs/AlGaAs two-dimensional electron system, the phase diagram of longitudinal resistivity \rho_xx in density and magnetic field plane exhibits an intriguing structure centered at filling factor \nu = 4 which is strikingly…

Mesoscale and Nanoscale Physics · Physics 2009-11-11 X. C. Zhang , I. Martin , H. W. Jiang

We present a phase diagram for a two-dimensional electron system with two populated subbands. Using a gated GaAs/AlGaAs single quantum well, we have mapped out the phases of various quantum Hall states in the density-magnetic filed plane.…

Mesoscale and Nanoscale Physics · Physics 2009-10-31 X. Y. Lee , H. W. Jiang , W. J. Schaff

Measurements in clean two-dimensional electron systems confined to wide GaAs quantum wells in which two electric subbands are occupied reveal an unexpected rotation of the orientation of the stripe phase observed at a half-filled Landau…

Mesoscale and Nanoscale Physics · Physics 2014-09-23 Yang Liu , D. Kamburov , M. Shayegan , L. N. Pfeiffer , K. W. West , K. W. Baldwin

We use time-dependent (current) density functional theory to study collective transitions between the two lowest subbands in GaAs/AlGaAs quantum wells. We focus on two systems where experimental results are available: a wide single and a…

Mesoscale and Nanoscale Physics · Physics 2009-10-31 C. A. Ullrich , G. Vignale

The thermodynamic potential of an ideal nonrelativistic gas of two-dimensional electrons in crossed uniform magnetic and electric fields is constructed. For low temperatures and very weak electric fields, it is shown that the Hall…

Condensed Matter · Physics 2007-05-23 Choon-Lin Ho , V. R. Khalilov , Chi Yang

In modern GaAs/Al$_x$Ga$_{1-x}$As heterostructures with record high mobilities, a two-dimensional electron gas (2DEG) in a quantum well is provided by two remote donor $\delta$-layers placed on both sides of the well. Each $\delta$-layer is…

Mesoscale and Nanoscale Physics · Physics 2018-07-16 M. Sammon , M. A. Zudov , B. I. Shklovskii

We realize a two-dimensional electron system (2DES) in ZnO by simply depositing pure aluminum on its surface in ultra-high vacuum, and characterize its electronic structure using angle-resolved photoemission spectroscopy. The aluminum…

Double layer two-dimensional electron systems at high perpendicular magnetic field are used to realize magnetic tunnel junctions in which the electrons at the Fermi level in the two layers have either parallel or anti-parallel spin…

Mesoscale and Nanoscale Physics · Physics 2017-05-10 J. P. Eisenstein , L. N. Pfeiffer , K. W. West

Here we report on a transparent method to characterize individual layers in a double-layer electron system which forms in a wide quantum well and to determine their electron densities. The technique relies on the simultaneous measurement of…

Mesoscale and Nanoscale Physics · Physics 2018-03-14 S. I. Dorozhkin , A. A. Kapustin , I. B. Fedorov , V. Umansky , K. von Klitzing , J. H. Smet

This is a commentary on two papers (PNAS 117 (51) 32244-32250 (2020) and arXiv:2011.06721), which observed a series of ordering transitions in a strongly correlated two-dimensional electron system confined to a AlAs quantum well. We…

Strongly Correlated Electrons · Physics 2021-01-26 Kyung-Su Kim , Steven A. Kivelson

We report low-dimensional tunneling in an independently contacted vertically coupled quantum wire system. This nanostructure is fabricated in a high quality GaAs/AlGaAs parallel double quantum well heterostructure. Using a novel flip chip…

Mesoscale and Nanoscale Physics · Physics 2009-11-10 E. Bielejec , J. A. Seamons , J. L. Reno , M. P. Lilly

The intriguing re-entrant integer quantized Hall states recently discovered in high Landau levels of high-mobility 2D electron systems are found to exhibit extremely non-linear transport. At small currents these states reflect insulating…

Mesoscale and Nanoscale Physics · Physics 2009-10-31 K. B. Cooper , M. P. Lilly , J. P. Eisenstein , L. N. Pfeiffer , K. W. West

Two dimensional InAs/GaAs quantum ring (QR) is considered using the effective potential approach. The symmetry of QR shape is violated as it is in the well-known Bohigas annular billiard. We calculate energy spectrum and studied the spatial…

Mesoscale and Nanoscale Physics · Physics 2012-12-05 I. Filikhin , S. G. Matinyan , B. Vlahovic

Experimental and theoretical evidence is presented for new low-magnetic-field ($B<5$ kG) 1/B-oscillations in the thermoelectric power of a high-mobility GaAs/AlGaAs two-dimensional (2D) electron gas. The oscillations result from…

Mesoscale and Nanoscale Physics · Physics 2009-11-10 Jian Zhang , S. K. Lyo , R. R. Du , J. A. Simmons , J. L. Reno

The longitudinal resistivity of two dimensional (2D) electrons placed in strong magnetic field is significantly reduced by applied electric field, an effect which is studied in a broad range of magnetic fields and temperatures in GaAs…

Mesoscale and Nanoscale Physics · Physics 2009-07-20 Jing Qiao Zhang , Sergey Vitkalov , A. A. Bykov

Flat bands near M points in the Brillouin zone are key features of honeycomb symmetry in artificial graphene (AG) where electrons may condense into novel correlated phases. Here we report the observation of van Hove singularity doublet of…