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arXiv · 2103.06865

Symmetry Indicators for Inversion-Symmetric Non-Hermitian Topological Band Structures

Pascal M. Vecsei·M. Michael Denner·Titus Neupert·Frank Schindler
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Abstract

We characterize non-Hermitian band structures by symmetry indicator topological invariants. Enabled by crystalline inversion symmetry, these indicators allow us to short-cut the calculation of conventional non-Hermitian topological invariants. In particular, we express the three-dimensional winding number of point-gapped non-Hermitian systems, which is defined as an integral over the whole Brillouin zone, in terms of symmetry eigenvalues at high-symmetry momenta. Furthermore, for time-reversal symmetric non-Hermitian topological insulators, we find that symmetry indicators characterize the associated Chern-Simons form, whose evaluation usually requires a computationally expensive choice of smooth gauge. In each case, we discuss the non-Hermitian surface states associated with nontrivial symmetry indicators.

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Pascal M. Vecsei, M. Michael Denner, Titus Neupert, Frank Schindler. 2021-03-11. Symmetry Indicators for Inversion-Symmetric Non-Hermitian Topological Band Structures. https://doi.org/10.1103/physrevb.103.l201114

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