Decoherence in Aharonov-Bohm rings

We study electron decoherence by measuring the temperature dependence of Aharonov-Bohm (AB) magnetoconductance oscillations in quasi-ID rings, etched in a high-mobility GaAs/GaAlAs heterostructure. The oscillation amplitude, which is quantified by Fast Fourier Transform (FFT) amplitudes, is influenced both by phase-breaking and by thermal averaging. FFT components of frequency up to six times the fundamental h/e component are observed and used in the analysis. It is crucial to study not only the h,e AB amplitude. but also the higher h,ne components, in order to distinguish the effects of phase-breaking and thermal averaging. For the phase-breaking. it is demonstrated that the damping of the oscillation amplitude is proportional to the length of the interfering paths. For temperatures T from 0.3 to 4 K we find the phase coherence length L-o infinity T-1. The phase coherence length does also seem to depend on sample geometry. Recently, the T-1 dependence has been predicted theoretically for AB rings by Seelig and Buttiker (Phys. Rev. B 64 (2001) 245313). (C) 2002 Elsevier Science B.V.. All rights reserved.