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Tsui, D. C.

Publications and source records attributed to Tsui, D. C..

At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Particle-Hole Symmetry and the Fractional Quantum Hall Effect in the Lowest Landau Level

Here, we report on detailed experimental studies of a high-quality heterojunction insulated-gate field-effect transistor (HIGFET) to probe the particle-hole symmetry of the fractional quantum Hall effect (FQHE) states about half-filling in the lowest Landau level. The HIGFET is specially designed to vary the density of a two-dimensional electronic system under constant magnetic fields. We find in our constant magnetic field, variable density measurements that the sequence of FQHE states at filling factors ν = 1/3, 2/5, 3/7… and its particle-hole conjugate states at filling factors 1-ν = 2/3, 3/5, 4/7… have a very similar energy gap. Moreover, a reflection symmetry can be established in the magnetoconductivities between the ν and 1-ν states about half-filling. Our results demonstrate that the FQHE states in the lowest Landau level are manifestly particle-hole symmetric.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2016

National High Magnetic Field Laboratory 2016 Annual Research Report: Termination of Two-Dimensional Metallic Conduction near the Metal-Insulator Transition in Si/SiGe Quantum Wells

The physical properties of two-dimensional (2D) electrons have been a subject of interest for a long time. Yet after many years of research, the ground states of a 2D electron system (2DES) in the presence of disorder and electron-electron interaction, a realistic situation in experiments, remain an open question. Recent observations of a downturn in conductivity at low temperatures in a Si/SiGe quantum well [1], Si-MOSFETs [2,3], and 2D holes in GaAs [4-6] seem to suggest that disorder plays an important role in the so-called 2D metal-insulator transition (MIT) and at T → 0 2DES may eventually become insulating. In this experiment, we focus on the downturn behavior as a function of spin polarization, which is varied by an in-plane magnetic field.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Impact of the modulation doping layer on the ν = 5/2 anisotropy

We have carried out a systematic study of the tilted magnetic field induced anisotropy at the Landau level filling factor ν = 5/2 in a series of high quality GaAs quantum wells, where the setback distance (d) between the modulation doping layer and the GaAs quantum well is varied from 33 to 164 nm. We have observed that in the sample of the smallest d, electronic transport is anisotropic when the in-plane magnetic field (B ip ) is parallel to the [1–10] crystallographic direction, but remains more or less isotropic when B ip // [110]. In contrast, in the sample of largest d, electronic transport is anisotropic in both crystallographic directions. Lastly, our results clearly show that the modulation doping layer plays an important role in the tilted field induced ν = 5/2 anisotropy.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2015

Fractional quantum Hall effect at Landau level filling ν = 4/11

In this study, we report low temperature electronic transport results on the fractional quantum Hall effect of composite fermions at Landau level filling ν = 4/11 in a very high mobility and low density sample. Measurements were carried out at temperatures down to 15mK, where an activated magnetoresistance R xx and a quantized Hall resistance R xy , within 1% of the expected value of h/(4/11)e 2 , were observed. The temperature dependence of the R xx minimum at 4/11 yields an activation energy gap of ~ 7 mK. Developing Hall plateaus were also observed at the neighboring states at ν = 3/8 and 5/13.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

Competing Quantum Hall Phases in the Second Landau Level in Low Density Limit

Up to date, studies of the fractional quantum Hall effect (FQHE) states in the second Landau level have mainly been carried out in the high electron density regime, where the electron mobility is the highest. Only recently, with the advance of high quality low density MBE growth, experiments have been pushed to the low density regime [1], where the electron-electron interactions are strong and the Landau level mixing parameter, defined by κ = e 2 /εI B /ℏω e , is large. Here, l B = (ℏe/B) 1/2 is the magnetic length and ω c = eB/m the cyclotron frequency. All other parameters have their normal meanings. It has been shown that a large Landau level mixing effect strongly affects the electron physics in the second Landau level [2].

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2014

Two-dimensional electron gas in monolayer InN quantum wells

We report in this letter experimental results that confirm the two-dimensional nature of the electron systems in a superlattice structure of 40 InN quantum wells consisting of one monolayer of InN embedded between 10 nm GaN barriers. The electron density and mobility of the two-dimensional electron system (2DES) in these InN quantum wells are 5 × 10{sup 15 }cm{sup −2} (or 1.25 × 10{sup 14 }cm{sup −2} per InN quantum well, assuming all the quantum wells are connected by diffused indium contacts) and 420 cm{sup 2}/Vs, respectively. Moreover, the diagonal resistance of the 2DES shows virtually no temperature dependence in a wide temperature range, indicating the topological nature of the 2DES.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗