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Theses

Courants permanents dans des anneaux mésoscopiques connectés

Abstract : Persistent currents in a ring threated by a magnetic flux is one of the most basic properties of mesoscopic physics. In the presence of a magnetic flux, a mesoscopic normal metal ring carries an equilibrium non-dissipative persistent current. Key experiements have confirmed the existence of persistent currents in isolated rings, although many experimental facts are still not well understood. In this context, an important question is to know if persistent currents can survive in a geometry of connected rings, the total size of the system being much longer than Lphi.
We have fabricated a sample with four and sixteen connected rings, etched in a gallium arsenide heterostructure. The magnetization due to persistent currents is detected with aluminium µ-squids, deposited on the top of the rings in order to have the best coupling. Moreover, metallic gates were included in order to have an accurate measurement of the noise level, and a calibration loop allows to have absolute magnetization measurements of the persistent currents in one ring.
Our experiment shows that the persistent currents still exist in a geometry where the rings are connected, the total length of the system being much longer than Lphi. Moreover, we have shown that the amplitude of the persistent currents is not significantly modified when connecting or isolating the rings. OUr results show that the persistent currents are not a specific property of isolated system smaller than Lphi : it is a robust effect that may be observed even in macroscopic samples.
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https://tel.archives-ouvertes.fr/tel-00069668
Contributor : Wilfried Rabaud <>
Submitted on : Friday, May 19, 2006 - 9:14:52 AM
Last modification on : Friday, December 18, 2020 - 1:34:04 PM
Long-term archiving on: : Monday, September 17, 2012 - 2:36:36 PM

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  • HAL Id : tel-00069668, version 1

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Wilfried Rabaud. Courants permanents dans des anneaux mésoscopiques connectés. Matière Condensée [cond-mat]. Université Joseph-Fourier - Grenoble I, 2001. Français. ⟨tel-00069668⟩

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