Non-Hermitian skin effect enforced by nonsymmorphic symmetries

Crystal symmetries play an essential role in band structures of non-Hermitian Hamiltonian. In this talk, we propose a non-Hermitian skin effect (NHSE) enforced by nonsymmorphic symmetries [1]. We show that the NHSE inevitably occurs if a two-dimensional non-Hermitian system satisfies conditions derived from the nonsymmorphic symmetry of the doubled Hermitian Hamiltonian. This NHSE occurs in symmetry classes with and without time-reversal symmetry. The NHSE enforced by nonsymmorphic symmetries always occurs simultaneously with the closing of the point gap at zero energy. We also show that such a NHSE can occur in specific three-dimensional space groups with nonsymmorphic symmetries.

[1] Y. Tanaka, R. Takahashi, and R. Okugawa, arXiv:2306.08923 (2023).