Out of equilibrium Anderson model: Conductance and Kondo temperature

• Published in: Physica. B, Condensed matter Vol. 407; no. 16; pp. 3263 - 3266
• Main Authors: Tosi, L., Roura-Bas, P., Llois, A.M., Aligia, A.A.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 15.08.2012; Elsevier
• Subjects: Anderson model; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Conductance; Electric potential; Electron states and collective excitations in thin films, multilayers, quantum wells, mesoscopic and nanoscale systems; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Exact sciences and technology; Fermi surfaces; Gates; Kondo temperature; Mathematical analysis; Mathematical models; Non-crossing approximation; Physics; Quantum dots; Quantum wells; Transport; Voltage; Anderson model; Conductance; Transport; Quantum dots; Kondo temperature; Non-crossing approximation; Temperature dependence; Localized states; Non crossing approximation; High temperature; Coulomb interaction; Repulsion interaction; Kondo effect; Fermi level; Transport processes; Linear response theory; Reliability
• ISSN: 0921-4526; 1873-2135
• DOI: 10.1016/j.physb.2011.12.082

We calculate the conductance through a quantum dot weakly coupled to metallic contacts by means of the Keldysh out of equilibrium formalism. We model the quantum dot with the SU(2) Anderson model and consider the limit of infinite Coulomb repulsion. The interacting system is solved with the numerical diagrammatic Non-Crossing Approximation (NCA) and the conductance is obtained as a function of temperature and gate voltage from differential conductance (dI/dV) curves. We discuss the results in comparison with those from the linear response approach which can be performed directly in equilibrium conditions. Comparison shows that out of equilibrium results are in good agreement with the ones from linear response supporting reliability of the method employed. The last discussion becomes relevant when dealing with general transport models through interacting regions. We also analyze the evolution of conductance vs gate voltage with temperature. While at high temperatures the conductance is peaked, when the Fermi energy coincides with the localized level it presents a plateau at low temperatures as a consequence of the Kondo effect. We discuss different ways to determine Kondo's temperature.