Electron phase coherence length in a lattice of antidots

Abstract

The temperature dependence of the phase coherence length Lϕ of electrons in a two-dimensional hexagonal lattice of antidots is investigated through weak localization (WL) measurements over a wide temperature range from 40mK to 30K. The magnetic field dependence of the WL can be perfectly described by the conventional theory for disordered conductors, with an additional magnetic-field-independent prefactor α. Using a two parameters fit of the WL, Lϕ can be extracted. An unusual T−1/4 dependence was found for Lϕ, which is contradictory with most of the models proposed for phase breaking processes. A saturation of Lϕ was observed below 1K. Finally, α was found to scale exponentially with the temperature. Surprisingly, the values obtained for α were particularly high, revealing mechanisms which enhance the WL in our system.