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TT: Fachverband Tiefe Temperaturen

TT 36: TR: Poster Session

TT 36.6: Poster

Donnerstag, 25. März 2010, 14:00–18:00, Poster A

Dephasing in a mesoscopic ring connected via arms to leads — •M. Treiber¹, O. M. Yevtushenko¹, F. Marquardt¹, J. von Delft¹, and I. V. Lerner² — ¹Physics Department, ASC, and CeNS, Ludwig-Maximilians-Universität, Theresienstrasse 37, 80333 Munich, Germany — ²School of Physics and Astronomy, University of Birmingham, Birmingham, B15 2TT, UK

We recently considered dephasing by electron interactions in an almost isolated ring using a model of homogeneous electron dissipation [1]. We showed that the amplitude of the Altshuler-Aronov-Spivak (AAS) oscillations crosses over to 0D behavior (Δ g_AAS ∼ T⁻²) when the temperature T drops below the Thouless energy. In the 0D regime, dephasing is dominated by large energy transfers, only restricted by T due to Pauli blocking. Therefore, the observation of this hitherto elusive crossover would allow quantitative tests of the role of T as UV-cutoff in the theory of dephasing. We discussed in [1] that by filtering Δ g_AAS from its nonoscillatory background, the influence of the leads, which may mask the predicted crossover, can be substantially reduced.

In this presentation, we consider a “lead-arm-ring-arm-lead” geometry, which is closer to the experimental situation. We assume absorbing leads and ballistic (not tunneling) contacts between arm and ring, having different numbers of conducting channels at both sides. We study the T dependence of the dephasing time, analyze in detail arm-ring cross contributions, which were neglected in [1], and discuss the possibility for an experimental observation of 0D dephasing in this model.

[1] M. Treiber et al., Phys. Rev. B 80, 201305(R) (2009).