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arXiv · 1810.06297

Exceptional rings in two-dimensional correlated systems with chiral symmetry

Tsuneya Yoshida·Robert Peters·Norio Kawakami·Yasuhiro Hatsugai
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Abstract

Emergence of exceptional points in two dimensions is one of the remarkable phenomena in non-Hermitian systems. We here elucidate the impacts of symmetry on the non-Hermitian physics. Specifically, we analyze chiral symmetric correlated systems in equilibrium where the non-Hermitian phenomena are induced by the finite lifetime of quasi-particles. Intriguingly, our analysis reveals that the combination of symmetry and non-Hermiticity results in novel topological degeneracies of energy bands which we call symmetry-protected exceptional rings (SPERs). We observe the emergence of SPERs by analyzing a non-Hermitian Dirac Hamiltonian. Furthermore, by employing the dynamical mean-field theory, we demonstrate the emergence of SPERs in a correlated honeycomb lattice model whose single-particle spectrum is described by a non-Hermitian Dirac Hamiltonian. We uncover that the SPERs survive even beyond the non-Hermitian Dirac Hamiltonian, which is related to a zero-th Chern number.

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Tsuneya Yoshida, Robert Peters, Norio Kawakami, Yasuhiro Hatsugai. 2018-11-26. Exceptional rings in two-dimensional correlated systems with chiral symmetry. https://doi.org/10.1103/physrevb.99.121101

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