Regensburg 2013 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 29: Transport: Quantum Dots, Wires, Point Contacts 3 (jointly with HL)

TT 29.3: Vortrag

Dienstag, 12. März 2013, 10:00–10:15, H20

Keldysh effective action theory for universal physics in spin-1/2 Kondo dots — •Sergey Smirnov and Milena Grifoni — Institut I - Theoretische Physik, Universität Regensburg, Universitätsstraße 31, D-93040 Regensburg, Deutschland

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 [1]. We apply our theory to the highly asymmetric Anderson model and describe its strong coupling limit, weak coupling limit and crossover region within a single analytical expression.

We further extend our theory to describe the Kondo regime when the quantum dot is placed in an external magnetic field. The modern experimental issues of the critical magnetic field, at which the zero bias maximum of the differential conductance starts to split into two maxima, as well as the distance between these maxima as a function of the magnetic field are also addressed.
[1] S. Smirnov and M. Grifoni, arXiv:1203.4360 (2012)