# Berlin 2018 – wissenschaftliches Programm

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# HL: Fachverband Halbleiterphysik

## HL 7: Topological insulators I (joint session HL/TT)

### HL 7.3: Vortrag

### Montag, 12. März 2018, 10:00–10:15, A 151

**Interplay between topology and disorder in a two-dimensional semi-Dirac material** — P V Sriluckshmy, •Kush Saha, and Roderich Moessner — Max Planck Institute for the Physics of Complex Systems, Dresden, Germany

We investigate the role of disorder in a two-dimensional semi-Dirac material characterized by a linear dispersion in one, and a parabolic dispersion in the orthogonal, direction. Using the self-consistent Born approximation, we show that disorder can drive a topological Lifshitz transition from an insulator to a semi-metal, as it generates a momentum independent off-diagonal contribution to the self-energy. Breaking time-reversal symmetry enriches the topological phase diagram with three distinct regimes– single-node trivial, two-node trivial and two-node Chern. We find that disorder can drive topological transitions from both the single- and two-node trivial to the two-node Chern regime. We further analyze these transitions in an appropriate tight-binding Hamiltonian of an anisotropic hexagonal lattice, by calculating the real-space Chern number. Additionally we compute the disorder-averaged entanglement entropy which signals both the topological Lifshitz and Chern transition as a function of the anisotropy of the hexagonal lattice. Finally, we discuss experimental aspects of our results.