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Phys. Rev. Lett. 95, 126603 (2005)

Probing the Kondo Density of States in a Three-Terminal Quantum Ring

R. Leturcq,1 L. Schmid,1 K. Ensslin,1 Y. Meir,2 D. C. Driscoll,3 and A. C. Gossard3

1Solid State Physics Laboratory, ETH Zrich, 8093 Zrich, Switzerland
2Department of Physics, Ben Gurion University, Beer Sheva 84105, Israel
3Materials Department, University of California, Santa Barbara, California 93106, USA

(Received 14 April 2005; published 15 September 2005)

We have measured the Kondo effect in a quantum ring connected to three terminals. In this configuration nonlinear transport measurements allow us to check which lead contributes to the Kondo density of states (DOS) and which does not. The ring geometry allows a fine-tuning of the coupling to each lead through the Aharonov-Bohm effect via application of a magnetic field. When the ring is connected to two strongly and one weakly coupled leads, conductance through the weakly coupled lead provides a direct measurement of the DOS in the Kondo regime. By applying a bias between the two strongly coupled leads, we demonstrate directly the splitting of the out-of-equilibrium Kondo DOS.

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