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TT: Tiefe Temperaturen

TT 11: Nanoelektronik I: Quantenpunkte, -dr
ähte, -punktkontakte

TT 11.3: Talk

Tuesday, March 9, 2004, 10:00–10:15, H19

Coulomb blockade and Non-Fermi-liquid behavior in quantum dots — •Frithjof Anders¹, Eran Lebanon², and Avraham Schiller² — ¹Insititut für Theoretische Physik, Universität Bremen, Postfach 330 440, D-28334 Bremen — ²Racah Institute of Physics, The Hebrew University, Jerusalem 91904, Israel

The non-Fermi-liquid properties of an ultrasmall quantum dot coupled to a lead and to a quantum box are investigated using a new variant of Wilson’s numerical renormalization group. Below the charging energy of the quantum box, a second screening channel is dynamically generated. Tuning the ratio of the tunneling amplitudes to the lead and box, we find a two-channel Kondo fixed point for arbitrary Coulomb repulsion on the dot, proving that the two-channel Kondo effect is far more generic to this setting than the original scenario of Oreg and Goldhaber-Gordon. At T = 0, a step-like structure is found in the conductance of a two-lead setting, the height of which depends on the dot occupancy. The temperature scale below which the two-channel Kondo effect sets in is greatly enhanced away from the local-moment regime, making this effect accessible in realistic devices.