Vertex Corrections' effects on diagrammatic approximations applied to the study of transport through a quantum dot

LEANDRO TOSI; PABLO ROURA-BAS; ANA MARÍA LLOIS

Capital Federal, Argentina

Otro; XII Giambiagi School, Dpto. Física UBA; 2010

Departamento de Fisica FCEyN Universidad de Buenos Aires

In the present work, we calculate the conductance through a single quantum dot weakly coupled to metallic contacts. We use the spin-1/2 Anderson model to describe the quantum dot, while considering a finite Coulomb repulsion. We solve the interacting system using the non-crossing-approximation (NCA) with finite U and the one-crossing approximation (OCA). These two solving schemes are non-perturbative diagrammatic approximations. We obtain the linear response conductance as a function of temperature and energy position of the localized level, within both approaches. From the comparison of both approximations we extract the role of the vertex corrections, which are introduced in the OCA calculations and neglected in the NCA scheme. We observe that the diagrams omitted within NCA are really important for appropriately describing transport phenomena in Kondo systems as well as in the mixed valence regime. These corrections are namely necessary to recover the universal scaling properties which appear when using numerical approaches such as the Numerical Renormalization Group(NRG).