Wed. seminar

[Cond.Matt. & Stat.Mech.Section]

   JOINT ICTP/SISSA CONDENSED MATTER SEMINAR





Luigi Stasi Seminar Room -     ICTP Leonardo Building   (first floor)



Wednesday, 28 April -     4:00 p.m.



David JACOB      (MPI fuer Mikrostrukturphysik, Halle, Germany)



"Kondo effect in nanoscopic conductors   with magnetic atoms"



Abstract



State of the art for calculating the current and conductance for  
atomic- and molecular-size junctions consists in combining ab initio  
electronic structure calculations on the level of Density Functional  
Theory (DFT) with the Landauer formalism.  This approach works quite  
well e.g. for metallic nanocontacts predicting zero-bias conductances  
that are in general in good agreement with the experiments.  However,  
this static mean-field approach cannot capture dynamical electron  
correlations that lead e.g. to the Kondo effect observed in STM  
experiments with magnetic adatoms and molecules on metal surfaces and  
more recently in nanocontacts made from ferromagnetic transition  
metals. In order to describe the dynamical correlations originating  
from the strongly interacting 3d-shells of transition metal atoms we  
have developed a new method that combines DFT based electronic  
structure calculations with  a fully dynamical treatment of the 3d- 
shells of the magnetic atoms in the so-called One-Crossing  
Approximation.  I will present results for Cu nanocontacts containing  
one or more magnetic impurities in the contact region. The strong  
dynamic correlations of the 3d electrons lead to quasi-particle  
resonances near the Fermi level that in turn give rise to Fano  
lineshapes in the conductance characteristics similar to those observe  
in recent experiments.