Dresden 2017 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 61: Correlated Electrons: (General) Theory 2
TT 61.2: Vortrag
Donnerstag, 23. März 2017, 09:45–10:00, HSZ 204
Dual Fermion Approach for the Honeycomb Lattice — •Daniel Hirschmeier1, Hartmut Hafermann2, and Alexander I. Lichtenstein1 — 1I. Institut für Theoretische Physik, Universität Hamburg, Germany — 2Mathematical and Algorithmic Sciences Lab, France Research Center, Huawei Technologies Co. Ltd., Paris
The study of strongly correlated electron systems remains a hot topic in modern condensed matter physics due to its rich phenomenology and its wide range of applications. Lately the material graphene has become one of the most frequently studied objects in this field, having a number of interesting properties arising due to its extraordinary crystal structure.
In this work we explore the consequences of correlation effects for electrons on a lattice with the very same structure, by applying the recently developed Dual Fermion approach to the Hubbard model on the honeycomb lattice. The Dual Fermion approach is a multiscale diagrammatic expansion around the Dynamical Mean Field Theory incorporating non-local correlations.
We show that the Dual Fermion approach describes the occurence of non-trivial correlation effects like the formation of extended Van Hove singularities in the quasiparticle spectrum close to Van Hove filling. Furthermore we investigate the Hubbard model on the honeycomb lattice at half-filling. Our results show an exponential scaling of antiferromagnetic fluctuations with temperature, which is in good agreement with analytical results and provide a revision of the semimetall-insulator scenario in DMFT.