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DS: Fachverband Dünne Schichten

DS 6: Graphene: Theory
(Joint session of DS, DY, HL, MA, O and TT organized by HL)

DS 6.5: Vortrag

Montag, 7. März 2016, 10:30–10:45, H17

Ab-initio lattice Monte-Carlo simulations of the Neck-disrupting Lifshitz transition in mono-layer graphene — •Michael Koerner, Dominik Smith, and Lorenz von Smekal — Institut fuer Theoretische Physik, Justus-Liebig-Universitaet Giessen

We study the effects of inter-electron interactions on the neck-disrupting Lifshitz transition, which is characterized by a change of topology of the Fermi surface. The Lifshitz transition is known to occur within a pure tight-binding description of mono-layer graphene when an external chemical potential drives the Fermi surface away from half-filling and across the saddles at the M-points. At these Van Hove singularities the density of states diverges logarithmically without interactions. We employ ab-intio Monte-Carlo simulations, which account for the full many-body physics of interacting electrons. We choose a partially screened Coulomb potential which combines the screening from localized electron states at short distances with the unscreened long-range Coulomb tails characteristic of graphene at half filling. Our goal is to determine whether interactions change the character of the topological transition, such that a real phase transition in the thermodynamic sense may occur, possibly in combination with chiral superconductivity.