Regensburg 2004 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 17: Postersitzung II: Transport, Quantenkoh
ärenz, Quantenflüssigkeiten
TT 17.33: Poster
Dienstag, 9. März 2004, 14:30–19:00, Poster A
Universal zero-bias anomaly in capacitatively coupled quantum dots — •Markus Garst1, Stefan Kehrein2, Thomas Pruschke3, Achim Rosch4, and Matthias Vojta1 — 1Institut für Theorie der Kondensierten Materie, Universität Karlsruhe, D-76128 Karlsruhe — 2Theoretische Physik III, Universität Augsburg, 86135 Augsburg — 3Institut für Theoretische Physik, Universität Göttingen, 37077 Göttingen — 4Institut für Theoretische Physik, Universität zu Köln, 50937 Köln
We analyze transport through a system of two capacitatively coupled Matveev dots [1] which is described by a model of two Ising-coupled Kondo impurities. The coupling between the dots controls a quantum phase transition [2], which we show [3] to be in the Kosterlitz–Thouless universality class. Exploiting the mapping to a generalized single-impurity Anderson model, we identify the critical theory as an effective cluster-Kondo model which can be treated analytically. The quantum phase transition results in pronounced signatures in the conductance G of the double dot system. Since the critical degrees of freedom of the electrons are solitonic excitations of the Fermi seas we obtain at the transition a characteristic zero-bias anomaly, G∼ |V|−2(√2−1) with an universal exponent. The phase diagram is analyzed with both the numerical renormalization group and the flow equation method.
[1] K. A. Matveev, Sov. Phys. JETP 72, 892 (1991).
[2] N. Andrei, G. T. Zimanyi and G. Schön, Phys. Rev. B 60 R5125 (1995).
[3] M. Garst et al., cond-mat/0310222