Regensburg 2013 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 60: Graphene - Theory (jointly with DS, HL, MA, and O)
TT 60.5: Vortrag
Donnerstag, 14. März 2013, 16:00–16:15, H17
RKKY Interaction in a Graphene Bilayer — •Nicolas Klier, Sam Shallcross, and Oleg Pankratov — Theoretische Festkörperphysik, Universität Erlangen-Nürnberg, Staudtstr. 7B2, 91058 Erlangen
RKKY interaction in doped graphene monolayer (kF≠0) shows Friedel oscillations decaying as 1/r2 [1]. In this work we consider the RKKY interaction in AA- and AB-stacked bilayer graphene using exact low energy Green’s functions. Apart from the common site-to-site interaction we discuss impurities located at the bond centers as well as impurities at the center of the hexagonal plaquettes and intercalant-type impurities located in-between the two carbon layers. Similarly to the monolayer case, we find an oscillatory 1/r2 decay for on-site impurities in AA-stacked bilayer graphene. The exchange integral separates into the product of an energy dependent oscillation and an additional modulation resulting from the interlayer coupling. Interestingly, for on-site impurities in AB-stacked bilayer graphene this additional modulation vanishes at low Fermi energies. Moreover, due to the interference of the neighboring site-to-site interactions, at high Fermi energies the RKKY interaction between two plaquette impurities shows a 1/r3 behavior.
[1] M. Sherafati and S. Satpathy, Phys. Rev. B 84, 125416, 2011