Dresden 2006 – scientific programme

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TT: Tiefe Temperaturen

TT 20: Transport: Nanoelectronics I - Quantum Dots, Wires, Point Contacts - Part 2

TT 20.1: Invited Talk

Tuesday, March 28, 2006, 14:00–14:30, HSZ 105

Theory of inelastic scattering from magnetic impurities — •Gergely Zarand^1,2, Laszlo Borda¹, Natan Andrei³, and Jan von Delft⁴ — ¹Budapest Univ. of Technology and Economics, Ungarn — ²Institut für Theoretische Festkörperphysik, Universität Karlsruhe — ³Rutgers University — ⁴LM Universität München

Inelastic processes play a crucial role in mesoscopic structures, where these processes destroy quantum interference effects. Recent experiments on quantum wires seem to support that much of these inelastic processes originate from magnetic impurities. Here we provide a framework that - at least at T=0 temperature - allows one to give a precise definition for the inelastic scattering rate and we show how this can be obtained for general quantum impurity models. As an example, we compute the full energy dependence of the inelastic scattering rate for the single channel Kondo problem using the non-perturbative machinery of numerical renormalization group. In contrast to naive expectations, we find a broad plateau of almost constant inelastic scattering rate for energies above the Kondo temperature, E>T_K, and a quasi-linear behavior below T_K, which crosses over to the expected Fermi liquid behavior, σ_inel(E) ∼ E²/T_K only at very small energies. This behavior compares well with recent experimental observations.