Regensburg 2013 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 58: Poster Session Transport & Matter at Low Temperature

TT 58.43: Poster

Donnerstag, 14. März 2013, 15:00–19:00, Poster D

Kondo effect in a graphene sheet with a vacancy — •Martin Sprengel and Fakher F. Assaad — Institut für theoretische Physik und Astrophysik, Universtität Würzburg, Am Hubland, D-97074 Würzburg, Germany

We study the influence of a single-atom vacancy in a Graphene lattice using a tight-binding model with nearest neighbour hopping and a Hubbard U term. The vacancy generates a localised state, which extends into the bulk with a power law. The question we wish to address is if under correlation effects a local moment is created and if it is ultimately screened by the bulk. To do so, we use continuous-time Quantum Monte Carlo (CT-QMC) simulations to calculate the dependence of the spin susceptibility on temperature, chemical potential and the Hubbard U. For small deviation from half-filling no sign problem occurs which allows us to benefit from the fact that CT-QMC is a numerically exact method. At half filling and down to our lowest temperatures we observe a Curie behaviour of the local spin susceptibility. Away from half filling, the very signature of the local moment is absent within the considered parameter range.