Dresden 2011 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 38: Poster Session Transport

TT 38.16: Poster

Wednesday, March 16, 2011, 14:00–18:00, P3

0.7 anomaly in QPC – temperature dependence of conductance in matsubara formalism — •Florian Bauer, Jan Heyder, and Jan von Delft — Arnold Sommerfeld Center, LMU München

To study the physics of the 0.7 anomaly in Quantum Point Contacts (QPCs), we calculate the conductance as a function of magnetic field and analyse the relevance of geometry. We study an extended 1D-Hubbard chain and model the QPC by a single smooth potential barrier. We use the functional renormalization group in Matsubara formalism to calculate the selfenergy and interaction vertex functions at Matsubara frequencies.

A calculation of the finite-temperature conductance for this chain model requires, in contrast to the SIAM, an analytic continuation to the real axis. We show that it is possible to avoid analytic continuation of the vertex function provided that the chain model is invariant under a L↔R parity transformation. For this case, we derive a conductance formula similar to the Meir-Wingreen formula, which expresses the conductance (including vertex contributions) purely in terms of two point correlators.