Quantum Coherence at Low Temperatures in Mesoscopic Systems: Effect of Disorder

Yasuhiro Niimi, Yannick Baines, Thibaut Capron, Dominique Mailly, Fang-Yuh Lo, Andreas D. Wieck, Tristan Meunier, Laurent Saminadayar, Christopher Bauerle

Published 2009-11-17, updated 2010-06-15Version 2

We study the disorder dependence of the phase coherence time of quasi one-dimensional wires and two-dimensional (2D) Hall bars fabricated from a high mobility GaAs/AlGaAs heterostructure. Using an original ion implantation technique, we can tune the intrinsic disorder felt by the 2D electron gas and continuously vary the system from the semi-ballistic regime to the localized one. In the diffusive regime, the phase coherence time follows a power law as a function of diffusion coefficient as expected in the Fermi liquid theory, without any sign of low temperature saturation. Surprisingly, in the semi-ballistic regime, it becomes independent of the diffusion coefficient. In the strongly localized regime we find a diverging phase coherence time with decreasing temperature, however, with a smaller exponent compared to the weakly localized regime.