Direkt zum Inhalt

Kern, Johannes ; Grifoni, Milena

Transport across an Anderson quantum dot in the intermediate coupling regime

Kern, Johannes and Grifoni, Milena (2013) Transport across an Anderson quantum dot in the intermediate coupling regime. Eur. Phys. J. B 86, p. 384.

Date of publication of this fulltext: 07 Oct 2013 11:00
Article
DOI to cite this document: 10.5283/epub.28880


Abstract

We describe linear and nonlinear transport across a strongly interacting single impurity Anderson model quantum dot with intermediate coupling to the leads, i.e. with tunnel coupling G of the order of the thermal energy k(B)T. The coupling is large enough that sequential tunneling processes (second order in the tunneling Hamiltonian) alone do not suffice to properly describe the transport ...

We describe linear and nonlinear transport across a strongly interacting single impurity Anderson model quantum dot with intermediate coupling to the leads, i.e. with tunnel coupling G of the order of the thermal energy k(B)T. The coupling is large enough that sequential tunneling processes (second order in the tunneling Hamiltonian) alone do not suffice to properly describe the transport characteristics. Upon applying a density matrix approach, the current is expressed in terms of rates obtained by considering a very small class of diagrams which dress the sequential tunneling processes by charge fluctuations. We call this the "dressed second order" (DSO) approximation. One advantage of the DSO is that, still in the Coulomb blockade regime, it can describe the crossover from thermally broadened to tunneling broadened conductance peaks. When the temperature is decreased even further (k(B)T < Gamma), the DSO captures Kondesque behaviours of the Anderson quantum dot qualitatively: we find a zero bias anomaly of the differential conductance versus applied bias, an enhancement of the conductance with decreasing temperature as well as universality of the shape of the conductance as function of the temperature. We can without complications address the case of a spin degenerate level split energetically by a magnetic field. In case spin dependent chemical potentials are assumed and only one of the four chemical potentials is varied, the DSO yields in principle only one resonance. This seems to be in agreement with experiments with pseudo spin [U. Wilhelm, J. Schmid, J. Weis, K. V. Klitzing, Physica E 14, 385 (2002)]. Furthermore, we get qualitative agreement with experimental data showing a cross-over from the Kondo to the empty orbital regime.



Involved Institutions


Details

Item typeArticle
Journal or Publication TitleEur. Phys. J. B
Publisher:SPRINGER
Place of Publication:NEW YORK
Volume:86
Page Range:p. 384
Date18 September 2013
InstitutionsPhysics > Institute of Theroretical Physics > Chair Professor Grifoni > Group Milena Grifoni
Identification Number
ValueType
10.1140/epjb/e2013-40618-9DOI
KeywordsNUMERICAL RENORMALIZATION-GROUP; SINGLE-ELECTRON TRANSISTOR; MAGNETIC-FIELD; MODEL; EQUILIBRIUM; CONDUCTANCE; FLUCTUATIONS; SYSTEMS; STATES; LIMIT;
Dewey Decimal Classification500 Science > 530 Physics
StatusPublished
RefereedUnknown
Created at the University of RegensburgYes
URN of the UB Regensburgurn:nbn:de:bvb:355-epub-288809
Item ID28880

Export bibliographical data

Owner only: item control page

nach oben