Abstract : We report on the measurement of phase coherence length in a high mobility two-dimensional electron gas patterned in two different geometries, a wire and a ring. The phase coherence length is extracted both from the weak localization correction in long wires and from the amplitude of the Aharonov-Bohm oscillations in a single ring, in a low temperature regime when decoherence is dominated by electronic interactions. We show that these two measurements lead to different phase coherence lengths, namely LwireΦ∝T−1/3LΦwire∝T−1/3 and LringΦ∝T−1/2LΦring∝T−1/2. This difference reflects the fact that the electrons winding around the ring necessarily explore the whole sample (ergodic trajectories), while in a long wire the electrons lose their phase coherence before reaching the edges of the sample (diffusive regime).
Auteurs:
Thibaut Capron 1 Christophe Texier 2, 3 Gilles Montambaux 3 Dominique Mailly 4 Andreas D. Wieck 5 Laurent Saminadayar 6
1 QuantECA – Circuits électroniques quantiques Alpes
2 LPTMS – Laboratoire de Physique Théorique et Modèles Statistiques
3 LPS – Laboratoire de Physique des Solides
4 LPN – Laboratoire de photonique et de nanostructures
5 Lehrstuhl für Angewandte Festkörperphysik
6 TPS – Thermodynamique et biophysique des petits systèmes
NEEL – Institut Néel
