# Kondo peaks and dips in the differential conductance of a multi-lead quantum dot: Dependence on bias conditions - Condensed Matter > Mesoscale and Nanoscale Physics

Abstract: We study the differential conductance in the Kondo regime of a quantum dotcoupled to multiple leads. When the bias is applied symmetrically on two of theleads $V$ and $-V$, as usual in experiments, while the others are grounded,the conductance through the biased leads always shows the expected enhancementat {\it zero} bias. However, under asymmetrically applied bias $V$ and$\lambda V$, with $\lambda>0$, a suppression - dip - appears in thedifferential conductance if the asymmetry coefficient $\lambda$ is beyond agiven threshold $\lambda 0= \sqrt3{1+r}$ determined by the ratio $r$ of thedot-leads couplings. This is a recipe to determine experimentally this ratiowhich is important for the quantum-dot devices. This finding is a direct resultof the Keldysh transport formalism. For the illustration we use a many-leadAnderson Hamiltonian, the Green functions being calculated in the Lacroixapproximation, which is generalized to the case of nonequilibrium.

Author: M. Tolea, I. V. Dinu, A. Aldea

Source: https://arxiv.org/