Phys. Rev. Lett. 95, 126603 (2005)
Probing the Kondo Density of States in a ThreeTerminal Quantum Ring
R. Leturcq,^{1} L. Schmid,^{1} K. Ensslin,^{1} Y. Meir,^{2} D. C. Driscoll,^{3} and A. C. Gossard^{3}
^{1}Solid State Physics Laboratory, ETH Zrich, 8093 Zrich, Switzerland
^{2}Department of Physics, Ben Gurion University, Beer Sheva 84105, Israel
^{3}Materials 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 finetuning of the coupling to each lead through^{ }the AharonovBohm 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 outofequilibrium Kondo DOS.
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A decrease of the Kondo peak height without significant increase of the
peak width has been obtained theoretically for a quantum dot in the
Kondo regime in weak interaction with a biased quantum point contact
26. This result has been interpreted as a suppression of the spectral
weight of the resonance near the Fermi level due to the interaction,
and an absence of dephasing.