Topological exceptional surfaces in non-Hermitian systems with parity-time and parity-particle-hole symmetries

Ryo Okugawa, Takehito Yokoyama

We study a topological band degeneracy in non-Hermitian systems with parity-time ($PT$) and parity-particle-hole ($CP$) symmetries. In $d$-dimensional non-Hermitian systems, it is…