Direct measurement of the phase coherence length in a GaAs/GaAlAs square network

Meydi Ferrier (1) , Lionel Angers (1) , Sophie Gueron (1) , Helene Bouchiat (1) , Christophe Texier (1, 2) , Gilles Montambaux (1) , Dominique Mailly (3) , Alistair C. H. Rowe (1)

1 LPS - Laboratoire de Physique des Solides
2 LPTMS - Laboratoire de Physique Théorique et Modèles Statistiques
3 LPN - Laboratoire de photonique et de nanostructures

The low temperature magnetoconductance of a large array of quantum coherentloops exhibits Altshuler-Aronov-Spivak oscillations which periodicitycorresponds to 1/2 flux quantum per loop.We show that the measurement of the harmonics content in a square networkprovides an accurate way to determine the electron phase coherence length$L_{\varphi}$ in units of the lattice length without any adjustableparameters.We use this method to determine $L_{\varphi}$ in a network realised from a 2Delectron gas (2DEG) in a GaAS/GaAlAs heterojunction. The temperaturedependence follows a power law $T^{-1/3}$ from 1.3 K to 25 mK with nosaturation, as expected for 1D diffusive electronic motion andelectron-electron scattering as the main decoherence mechanism.

Mots clés: Coherence de phase; localisation faible

Domaines: Systèmes mésoscopiques et effet Hall quantique [cond-mat.mes-hall]; Systèmes désordonnés et réseaux de neurones [cond-mat.dis-nn]

Meydi Ferrier, Lionel Angers, Sophie Gueron, Helene Bouchiat, Christophe Texier, et al.. Direct measurement of the phase coherence length in a GaAs/GaAlAs square network. Physical Review Letters, 2004, 93, pp.246804. ⟨10.1103/PhysRevLett.93.246804⟩. ⟨hal-00001168v2⟩