Berlin 2015 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 12: Graphene: mostly Theory (with O/TT)

HL 12.9: Vortrag

Montag, 16. März 2015, 17:00–17:15, ER 164

Behaviour of the edge states of the ν=0 lowest Landau level in graphene beyond SU(4)-symmetry — •Angelika Knothe^1,2 and Thierry Jolicoeur² — ¹Physikalisches Institut, Albert-Ludwigs-Universität Freiburg, Hermann-Herder-Str. 3, 79104 Freiburg — ²Université Paris Sud, CNRS, LPTMS, UMR 8626, Orsay 91405 France

The ν=0 quantum Hall state of an infinite sheet of graphene is known to exhibit various different phases when the SU(4)-symmetry of spin and valley/sublattice isospin is broken by interactions and the Zeeman-effect [1]. The situation becomes even richer when considering the edge states close to the sharp boundaries of a finite piece of graphene: Recent theoretical [2] and experimental [3] works suggest that in finite samples the properties of the spin and isospin-texture and its excitations depend on the position within the lattice with respect to its edge. With the help of numerical Hartree-Fock calculations we theoretically investigate the behaviour of the edge modes of a ν=0 quantum Hall state of graphene. In our model-Hamiltonian we account for both, the influence of SU(4)-symmetric terms and such that break the symmetry, as well as for the presence of the boundary of the lattice. In doing so, we are able to understand the behaviour of different spin and isospin configurations as compared to the phases in the bulk or the predictions of a non-interacting single-electron theory [4].

[1] M. Kharitonov, Phys. Rev. B 85, 155439 (2012) [2] G. Murthy et al., Phys. Rev. B 90, 241410(R) (2014) [3] G. Li et al., Nature Commun. 4, 1744 (2013) [4] D. A. Abanin et al., Phys. Rev. Lett. 96, 176803 (2006)