ELFT HÍRADÓ

[Varga Imre <varga AT neumann.phy.bme.hu>]

                                               MEGHIVO
                      a BME Fizikai Intezet, Elmeleti Fizika Tanszek
                                           szeminariumara:


                                              Jens Paaske
                 The Niels Bohr Institute & The Nano-Science Centre, 
                                        Copenhagen, Denmark

                     "Non-equilibrium Singlet-Triplet Kondo Effect

        Abstract: The Kondo effect has become a common signature in 
bias-spectroscopy           
        of single-electron transistors such as GaAs quantum dots and 
single-molecule 
        transistors.  Whereas zero-bias conductance-anomalies are rather well 
        understood, it remains uncertain to what extent Kondo correlations 
persist in 
        conductance-anomalies observed at finite bias-voltage. A finite 
applied bias 
        may compensate the gap between singlet and triplet states in a doubly 
        occupied quantum dot and will thereby support inelastic spin-flips 
and lead 
        to resonant exchange-tunnelling. However, the finite bias-voltage 
leaves us 
        with a genuine non-equilibrium problem involving voltage-dependent 
        spin-polarization as well as strong decoherence effects. In this 
talk, I 
        will present a perturbative renormalization group calculation for a   
  
        singlet-triplet Kondo effect induced by a finite bias voltage, 
treating         weak    
        Kondo-correlations alongside with these non-equilibrium effects. A    
          
        comparison to recent measurements on a single-walled Carbon nanotube 
        will be presented. [J. Paaske, A. Rosch, P. Woelfle,,  N. Mason, C. 
M. 
        Marcus & J. Nygaard,, Nat. Phys. 2, 460 (2006) 
        <http://www.nature.com/nphys/journal/v2/n7/full/nphys340.html>]


        Helye: BME Fizikai Intezet,
                   Elmeleti Fizika Tanszek
                   Budafoki ut 8.
                   F-epulet, III. lepcsohaz, mfszt. Szeminariumi szoba

        Ideje: 2006. oktober 20. pentek, 10:15.


        Minden erdeklodot szivesen latunk.



                                                                              
  Varga Imre