Berlin 2018 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 13: Graphene: Electronic Properties, Structure and Substrate Interaction I (joint session O/TT)

TT 13.10: Vortrag

Montag, 12. März 2018, 12:45–13:00, MA 043

A novel delocalized phase in the small angle graphene twist bilayer — •Maximilian Fleischmann, Reena Gupta, Dominik Weckbecker, and Sam Shallcross — Theoretische Festkörperphysik, FAU Erlangen-Nürnberg, Staudtstrasse 7/B2, 91058 Erlangen, Germany

In this work we demonstrate that the small angle limit of the graphene twist bilayer contains, in addition to its well known localized phase [1], a novel delocalized phase accessible by applied interlayer bias. This phase differs profoundly from the large angle delocalized phase as, in contrast to the almost perfectly circular Fermi surface found at large angles, one finds almost perfectly linear Fermi lines. These may be translated into each other by a so-called nesting vector, the magnitude of which is controllable by the applied field. The finding of a phase in the twist bilayer consisting solely of one dimensional Fermi lines connected by field tunable nesting vectors, marks this system out as an unexpected playground for the study of nested Fermiology and electronic instabilities.

[1] D. Weckbecker et al., Phys. Rev. B 93, 035452, 2016.