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Etude du transport électronique dans des systèmes mésoscopiques : interféromètre à anneau

Abstract : The present work deals with the study of transport properties of an interferential system, fabricated at the interface of a modulation doped AlGaAs/GaAs semiconductor heterostructure. The principle of this electron interferometer is based on the solid state Aharonov-Bohm effect. This effect is due to the influence of an electromagnetic field on the phase of the electron wave function. We have measured high mobility samples, in which the phase coherence length Lphi is greater than the dimensions of the system, in the ballistic transport regime. First, we investigate the temperature dependence of AB oscillations. We show that the results can be understood in terms of transmission probability through the eigenstates of the ring. A numerical model based on weak coupling between the ring and the leads fits the experimental data, provided that we take into account the charging energy due to Coulomb repulsions. Other experimental results strengthen this assumption of weak coupling. When the gate voltage, which cover the entire structure, i.e both arms, is swept in a continuous way, the phase of the oscillations of magnetoresistance switches between 0 and pi. These changes are accompanied by intermediate h/2e oscillations. Similar effects are observed when a DC-bias current is applied. These measurements suggest that the electronic properties of the ring are directly connected to the energy spectrum, so that we have performed a spectroscopic investigation of a mesoscopic ring.
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https://tel.archives-ouvertes.fr/tel-00004616
Contributor : Mikaël Cassé <>
Submitted on : Monday, February 16, 2004 - 12:35:03 PM
Last modification on : Thursday, January 11, 2018 - 6:14:42 AM
Long-term archiving on: : Wednesday, September 12, 2012 - 1:20:17 PM

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Mikaël Cassé. Etude du transport électronique dans des systèmes mésoscopiques : interféromètre à anneau. Matière Condensée [cond-mat]. INSA de Toulouse, 2001. Français. ⟨tel-00004616⟩

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