Veranstaltungsdetails

9.8.2011, 17:00
Jungiusstr. 11, Hörsaal AP

SFB 668 - Kolloquium

Prof. Dr. Eugene Kogan (Bar-Ilan University, Israel):

On RKKY interaction in graphene

We analytically study the exchange interaction J between two magnetic impurities in graphene (the RKKY interaction) in the linear approximation for the electrons dispersion law, using standard quantum mechanics perturbation theory (off-the-energy shell perturbation theory). The approach turns out to be simpler than that, implemented in the Green?s function approach and based on the off-the-mass shell perturbation theory, and allows to evade some problems connected with the latter. We also present a new proof of the theorem, which states that the RKKY interaction on the bipartite lattice at half filling is ferromagnetic between magnetic impurities on the same sublattice and is antiferromagnetic between impurities on opposite sublattices, based on the perturbation theory for the thermodynamic potential.