Topological properties of a spin-orbit coupled Su-Schrieffer-Heeger model co-modulated by imaginary potential and nonreciprocity

Abstract

This paper investigates the topological properties and spectral characteristics of a nonreciprocal spin-orbit-coupled Su-Schrieffer-Heeger model with complex gain and loss potentials. It is found that, as the imaginary potential increases, the originally fourfold-degenerate zero-energy states are suppressed, accelerating the transition of originally purely real eigenstates into the complex ones. The interplay between the imaginary potential and nonreciprocal hopping strength drives a topological phase transition in the system, leading to the emergence of new topological phases. The introduction of the imaginary potential broadens the range of doubly degenerate zero-energy states and generates a gapless phase in the region where the intracell hopping is negative. All these results provide theoretical support for exploring the competition between imaginary potentials and nonreciprocal coupling in spin-orbit-coupled systems. This work contributes to the understanding of topological phase transitions and the non-Hermitian skin effect in nonreciprocal systems.