Enhancements in Two Dimensional Electron Gas Density and Mobility in δ-Doped AiGaAs Heterostructures

1987 ◽  
Vol 102 ◽  
Author(s):  
J. E. Cunningham ◽  
G. L Timp ◽  
E. F. Schubert ◽  
W. T. Tsang ◽  
P. G. N. DeVegvar ◽  
...  
Keyword(s):  
Quantum Hall Effect ◽  
Electron Gas ◽  
Quantum Hall ◽  
Fractional Quantum Hall Effect ◽  
Dimensional Electron ◽  
Two Dimensional Electron Gas ◽  
Fractional Quantum ◽  
Fractional Quantum Hall ◽  
Dimensional Electron Gas ◽  
B Doping

ABSTRACTWe report our recent investigations of a new structure formed by b-doping the barrier of an AlGaAs/GaAs heterostructure. In this new structure we have observed both a mobility of 1.9×lO6cm2/Vsec and the fractional quantum hall effect. We compare low temperature mobilities and densities achieved with the δ-doped heterostructure with corresponding high values reported in the literature for the homogeneously- doped heterostructure. We show that systematic enhancements in both density and mobility occur in the b-doped heterostructure. By δ-doping both barriers of a quantum well we have also achieved electron concentrations of 4×1012cm -2 in the well.

scholarly journals 3/2 fractional quantum Hall plateau in confined two-dimensional electron gas

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Hailong Fu ◽  
Yijia Wu ◽  
Ruoxi Zhang ◽  
Jian Sun ◽  
Pujia Shan ◽  
...  
Keyword(s):  
Electron Gas ◽  
Quantum Hall ◽  
Two Dimensional ◽  
Dimensional Electron ◽  
Two Dimensional Electron Gas ◽  
Fractional Quantum ◽  
Edge Structure ◽  
Fractional Quantum Hall ◽  
Lateral Confinement ◽  
Dimensional Electron Gas

Abstract Even-denominator fractional quantum Hall (FQH) states, such as 5/2 and 7/2, have been well known in a two-dimensional electron gas (2DEG) for decades and are still investigated as candidates of non-Abelian statistics. In this paper, we present the observation of a 3/2 FQH plateau in a single-layer 2DEG with lateral confinement at a bulk filling factor of 5/3. The 3/2 FQH plateau is quantized at $$\left( {\frac{h}{{e^2}}} \right)/\left( {\frac{3}{2}} \right)$$ h e 2 ∕ 3 2 within 0.02%, and can survive up to 300 mK. This even-denominator FQH plateau may imply intriguing edge structure and excitation in FQH system with lateral confinement. The observations in this work demonstrate that understanding the effect of the lateral confinement on the many-body system is critical in the pursuit of important theoretical proposals involving edge physics, such as the demonstration of non-Abelian statistics and the realization of braiding for fault-tolerant quantum computation.

scholarly journals Competition of Pairing and Nematicity in the Two-Dimensional Electron Gas

2020 ◽  
Vol 11 (1) ◽  
pp. 17-35 ◽  
Author(s):  
Katherine A. Schreiber ◽  
Gábor A. Csáthy
Keyword(s):  
Electron Gas ◽  
Quantum Hall ◽  
Landau Levels ◽  
Composite Fermions ◽  
Dimensional Electron ◽  
Two Dimensional Electron Gas ◽  
Fractional Quantum ◽  
Fractional Quantum Hall ◽  
Dimensional Electron Gas ◽  
Quantum Hall State

Due to its extremely rich phase diagram, the two-dimensional electron gas exposed to perpendicular magnetic fields has been the subject of intense and sustained study. One particularly interesting problem in this system is that of the half-filled Landau level, where the Fermi sea of composite fermions, a fractional quantum Hall state arising from a pairing instability of the composite fermions, and the quantum Hall nematic were observed in the half-filled N = 0, N = 1, and N ≥ 2 Landau levels, respectively. Thus, different ground states developed in different half-filled Landau levels. This situation has recently changed, when evidence for both the paired fractional quantum Hall state and the quantum Hall nematic was reported in the half-filled N = 1 Landau level. Furthermore, a direct quantum phase transition between these two ordered states was found. These results highlight an intimate connection between pairing and nematicity, which is a topic of current interest in several strongly correlated systems, in a well-understood and low-disorder environment.

Can fractional quantum Hall effect be due to the formation of coherent wave structures in a 2D electron gas?

2016 ◽  
Vol 30 (13) ◽  
pp. 1650142
Author(s):  
Babur M. Mirza
Keyword(s):  
Hall Effect ◽  
Quantum Hall Effect ◽  
Electron Gas ◽  
Density Wave ◽  
Quantum Hall ◽  
Microscopic Theory ◽  
Fractional Quantum Hall Effect ◽  
Hall Resistance ◽  
Fractional Quantum ◽  
Fractional Quantum Hall

A microscopic theory of integer and fractional quantum Hall effects is presented here. In quantum density wave representation of charged particles, it is shown that, in a two-dimensional electron gas coherent structures form under the low temperature and high density conditions. With a sufficiently high applied magnetic field, the combined [Formula: see text] particle quantum density wave exhibits collective periodic oscillations. As a result the corresponding quantum Hall voltage function shows a step-wise change in multiples of the ratio [Formula: see text]. At lower temperatures further subdivisions emerge in the Hall resistance, exhibiting the fractional quantum Hall effect.

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