Berlin 2015 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 71: Correlated Electrons: Poster Session
TT 71.12: Poster
Wednesday, March 18, 2015, 15:00–18:00, Poster B
Cobalt adatoms on Graphene: role of the realistic interaction matrix in a QMC simulation — •Igor Krivenko1, Maria Valentyuk1, Ersoy Sasioglu2, Priyanka Seth3, Michel Ferrero3, Olivier Parcollet4, and Alexander Lichtenstein1 — 1I. Institut für Theoretische Physik, Universität Hamburg — 2Peter Grünberg Institute and Institute for Advanced Simulation, Forschungszentrum Jülich — 3Centre de Physique Théorique, École Polytechnique, France — 4Institut de Physique Théorique, CEA-Saclay, France
We have theoretically studied the local spectra and magnetic properties of the cobalt impurities on the graphene at the low temperatures. In our studies we have employed the DFT++ method in the projector augmented wave (PAW) basis set using the VASP code, and a new hybridization expansion CT-QMC solver from the TRIQS project (Toolbox for Research on Interacting Quantum Systems). We have been interested in the observation of the spin and orbital Kondo effect in the different adatom geometries (hollow-position/top-position). Another question of the interest has been to study the effect of different approximations for the local interaction matrix on the impurity spectrum. In order to reproduce the multiplet structure of the cobalt d-shell, one has to consider interactions beyond a simple density-density approximation. With our new hybridization expansion solver we have been able to treat a U-matrix, parametrized by 3 Slater integrals (129 non-vanishing matrix elements) and a realistic U-matrix, obtained by means of the Constrained RPA method (157 elements).