### Abstract

We study the Kane-Mele-Hubbard model with an additional inversion-symmetry-breaking term. Using the topological Hamiltonian approach, we calculate the Z 2 invariant of the system as function of spin-orbit coupling, Hubbard interaction U , and inversion-symmetry-breaking onsite potential. The phase diagram calculated in that way shows that, on the one hand, a large term of the latter kind destroys the topological nontrivial state. On the other hand, however, this inversion-symmetry-breaking field can enhance the topological state since for moderate values the transition from the nontrivial topological to the trivial Mott insulator is pushed to larger values of interaction U . This feature of an enhanced topological state is also found on honeycomb ribbons. With inversion

symmetry, the edge of the zigzag ribbon is magnetic for any value of U . This magnetic moment destroys the gapless edge mode. Lifting inversion symmetry allows for a finite region in interaction strength U below which gapless edge modes exist.

symmetry, the edge of the zigzag ribbon is magnetic for any value of U . This magnetic moment destroys the gapless edge mode. Lifting inversion symmetry allows for a finite region in interaction strength U below which gapless edge modes exist.

Original language | English |
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Article number | 165169 |

Journal | Physical Review / B |

Volume | 94 |

DOIs | |

Publication status | Published - 26 Oct 2016 |

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### Fields of Expertise

- Advanced Materials Science

### Treatment code (Nähere Zuordnung)

- Basic - Fundamental (Grundlagenforschung)
- Theoretical

### Cooperations

- NAWI Graz