9.8.2011, 17:00 Jungiusstr. 11, Hörsaal AP | SFB 668 - Kolloquium Prof. Dr. Eugene Kogan (Bar-Ilan University, Israel): On RKKY interaction in grapheneWe 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. |