Abstract
We study the differential conductance in the Kondo regime of a quantum dot coupled to multiple leads. When the bias is applied symmetrically on two of the leads ( and , as usual in experiments) while the others are grounded, the conductance through the biased leads always shows the expected enhancement at zero bias. However, under asymmetrically applied bias ( and , with ), a suppression—dip—appears in the differential conductance if the asymmetry coefficient is beyond a given threshold determined by the ratio of the dot-lead couplings. This is a recipe to determine experimentally this ratio which is important for the quantum-dot devices. This finding is a direct result of the Keldysh transport formalism. For the illustration we use a many-lead Anderson Hamiltonian, the Green’s functions being calculated in the Lacroix approximation, which is generalized to the case of nonequilibrium.
- Received 13 May 2008
DOI:https://doi.org/10.1103/PhysRevB.79.033306
©2009 American Physical Society