Intrinsic-perturbation induced anomalous higher-order boundary states in non-Hermitian systems

Abstract

The behavior of higher-order boundary states in non-Hermitian systems is elusive and thereby finding the mechanism behind these states is both essential and significant. Here, we uncover a novel mechanism that induces anomalous higher-order boundary states. The mechanism originates from the sensitivity of the non-normal boundary Hamiltonian to intrinsic perturbations, where intrinsic perturbations here refer to the influence of the bulk on the topological boundaries. Based on the mechanism, we reveal a new kind of phase transition, i.e., the transition between hybrid skin-topological states and scale-free topological boundary states. We also find that scale-free topological boundary states exhibit size-dependent spectra, influencing the existence of higher-order topological boundary states. Unlike conventional hybrid skin-topological states or higher-order non-Hermitian skin effect, the above two kinds of anomalous higher-order boundary states exhibit size-dependent characteristics. Our work opens a new horizon for the control of higher-order boundary states and topological properties of non-Hermitian systems.

4.7 pages, 3 figures in the main text; 16 pages, 10 figures in the Supplemental Material

References in corpus (4)

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• Topological Defects and Gapless Modes in Insulators and Superconductors
• Disorder-driven Phase Transitions of Second-order Non-Hermitian Skin Effects