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

Abstract : 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 lengthLφLφ in units of the lattice length without any adjustableparameters.We use this method to determine LφLφ in a network realised from a 2Delectron gas (2DEG) in a GaAS/GaAlAs heterojunction. The temperaturedependence follows a power law T−1/3T−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.

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