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WS18/19 – Abstract
Dominik Smith
(Gießen University)
7.2.2019
Quantum Phase transitions on the hexagonal lattice (PRETALK for students at 15:30 h)
Graphene, a system of carbon atoms arranged on a two dimensional hexagonal lattice, has been the subject of intense theoretical and experimental research in the past decade, due to its unique electronic properties. The special symmetries of its electronic band structure lead to an effective description in terms of a massless Dirac field, and strong inter-electron interactions, which can be tuned through various experimental techniques, drive quantum phase transitions to different gapped electronic ordered phases. The phase diagram of interacting fermions on a hexagonal lattice can be studied from first principles using Hybrid-Monte-Carlo simulations. These unambiguously show that including a long-range inter-electron potential is of major importance and provide strong evidence that the transition from a semimetal to an insulating spin-density-wave phase, in the presence of an unscreened Coulomb tail, is a “conformal” phase transition of infinite order, characterized by exponential rather than powerlaw scaling. Here, the present status of these efforts is reported.
