Keldysh effective action theory for universal physics in spin-1/2 Kondo dots

Abstract

We present a theory for the Kondo spin-1/2 effect in strongly correlated quantum dots. The theory is applicable at any temperature and voltage. It is based on a quadratic Keldysh effective action parameterized by a universal function. We provide a general analytical form for the tunneling density of states through this universal function for which we propose a simple microscopic model. We apply our theory to the highly asymmetric Anderson model with $U=\infty$ and describe its strong coupling limit, weak coupling limit and crossover region within a single analytical expression. We compare our results with numerical renormalization group in equilibrium and with a real-time renormalization group out of equilibrium and show that the universal shapes of the linear and differential conductance obtained in our theory and in these theories are very close to each other in a wide range of temperatures and voltages. In particular, as in the real-time renormalization group, we predict that at the Kondo voltage the differential conductance is equal to 2/3 of its maximum.

5 pages, 2 figures + supp.mat

References in corpus (3)

• The numerical renormalization group method for quantum impurity systems
• Electric-field controlled spin reversal in a quantum dot with ferromagnetic contacts
• Universal Scaling in Non-equilibrium Transport Through a Single-Channel Kondo Dot

Cited by in corpus (5)

• Conductance scaling in Kondo correlated quantum dots: role of level asymmetry and charging energy
• Kondo model in nonequilibrium: Interplay between voltage, temperature, and crossover from weak to strong coupling
• Transport properties of fully screened Kondo models
• Infinite Grassmann Time-Evolving Matrix Product Operator Method in the Steady State
• The generic fixed point model for pseudo-spin-1/2 quantum dots in nonequilibrium: Spin-valve systems with compensating spin polarizations