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HL: Fachverband Halbleiterphysik

HL 87: Low-dimensional systems: Topological order 2 (TT with DS/HL/MA/O)

HL 87.13: Vortrag

Donnerstag, 19. März 2015, 18:15–18:30, H 3010

An analytical study of the entanglement spectrum of graphene bilayers — •Sonja Predin and John Schliemann — Institute for Theoretical Physics, University of Regensburg, D-93040 Regensburg, Germany

We present an analytical study of the entanglement spectrum of graphene bilayers. The entanglement spectrum has been proposed as a ground state property that exhibits characteristic energy excitations[1]. Futhermore, it was claimed that gapless systems possess the same number of Dirac cones as their entanglement spectrum [2]. In addition, it was suggested that the entanglement spectrum is a promising tool to characterize topological phases. In this work we will show that the energy spectrum of an gapless system and its entanglement spectrum can have a different topology. In particular, we will show that Lifshitz transitions change the topology of the energy spectrum of graphene bilayers in a different way than the topology of entanglement spectrum. The topology of the energy spectrum of graphene bilayers for small energies is changed by Lifshitz transitions by changing the connectivity by the appearance of the three additional Dirac cones around every Dirac point [3]. The entanglement spectrum, on the other hand, is changed by deforming a Dirac cone into a neck charaterized by vanishing eigenvalues of the entanglement Hamiltonian.

[1] H. Li and F. D. M. Haldane,

Phys. Rev. Lett. 101, 010504 (2008)

[2] A. M. Turner, et al., Phys. Rev. B, 82, 241102R (2010)

[3] J. Cserti, et al., Phys. Rev. Lett. 99, 066802 (2007)