Dresden 2017 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 30: Correlated Electrons: Quantum Impurities, Kondo Physics
TT 30.2: Talk
Tuesday, March 21, 2017, 14:15–14:30, HSZ 03
Numerical Renormalization Group study of Gate Induced Kondo Screening in Graphene — •Daniel May1, Jinhai Mao2, Yuhang Jiang2, Po-Wei Lo3,4, Guohong Li2, Guang-Yu Guo3,4, Frithjof Anders1, and Eva Y. Andrei2 — 1Technische Universität Dortmund, Lehrstuhl für Theoretische Physik 2, Germany — 2Rutgers University, Department of Physics and Astronomy, USA — 3National Taiwan University, Department of Physics, Taiwan — 4National Center for Theoretical Sciences, Physics Division, Taiwan
Graphene in its pristine form has transformed our understanding of 2D electron systems leading to fundamental discoveries. When graphene’s honeycomb lattice is disrupted by single atom vacancies, new phenomena, namely a re-entrance Kondo effect, may emerge. We present numerical renormalization group (NRG) calculations for a two-orbital model consisting of a local σ orbital and a localized π state induced by the vacancy. Guided by ab-initio calculations for the parameters we determine two regimes. The re-entrance regime (i) is characterized by a conventional Kondo effect (p doping), a breakdown of the Kondo peak for vanishing chemical potential |µ| → 0, and a underscreened Kondo (n doped) where the π conduction band is screening the magnetic moment of the σ orbital. Increasing the hybridization between the σ orbital and the π conduction band further drives the system into the second regime (ii) where the π state is depopulated and a conventional Kondo effect is present (p doped).