Climbing the entropy barrier: driving the single- towards the multichannel Kondo effect by a weak coulomb blockade of the leads.
We study a model proposed recently in which a small quantum dot is coupled symmetrically to several large quantum dots characterized by a charging energy E(c). Even if E(c) is much smaller than the Kondo temperature T(K), the long-ranged interactions destabilize the single-channel Kondo effect and induce a flow towards a multichannel Kondo fixed point associated with a rise of the impurity entropy with decreasing temperature. Such an "uphill flow" implies a negative impurity specific heat, in contrast with all systems with local interactions. An exact solution found for a large number of channels allows us to capture this physics and to predict transport properties.
Florens
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S
Institut für Theorie der Kondensierten Materie, Universität Karlsruhe, 76128 Karlsruhe, Germany.
Rosch
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A