Experimental evidence of a metal-insulator transition in a half-filled Landau level

We have measured the low-temperature transport properties of a high-mobility front-gated GaAs/Al_{0.33}Ga_{0.67}As heterostructure. By changing the applied gate voltage, we can vary the amount of disorder within the system. At a Landau level filling factor $\nu =1/2$, where the system can be described by the composite fermion picture, we observe a crossover from metallic to insulating behaviour as the disorder is increased. Experimental results and theoretical prediction are compared.Comment: To be published in Solid State Communications. 4 figure

The Aharonov-Bohm Effect in the Fractional Quantum Hall Regime

We have investigated experimentally resonant tunnelling through single-particle states formed around an antidot by a magnetic field, in the fractional quantum Hall regime. For 1/3 filling factor around the antidot, Aharonov-Bohm oscillations are observed with the same magnetic field period as in the integer quantum Hall regime. All our measurements are consistent with quasiparticles of fractional charge e*. However, the results are also consistent with particles of any charge (>= e*) as the system must rearrange every time the flux enclosed increases by h/e.Comment: Postscript, 4 pages, gzipped (350 kB

The physics and fabrication of GaAs/AlGaAs ballistic electron devices

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Electron relaxation times in high-carrier-density GaAs-(Ga,Al)As heterojunctions

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A new mechanism for high-frequency rectification in a ballistic quantum point-contact

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Observations of plasmons and edge magnetoplasmons in voltage-tunable dots in GaAs/AlGaAs heterostructures

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A novel mechanism for parallel conduction in GaAs-(Ga,Al)As heterojunctions

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LETTER TO THE EDITOR: Ballistic transport in one dimension: additional quantisation produced by an electric field

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