Hybrid scaling theory of localization transition in a non-Hermitian disorder Aubry-André model

Abstract

In this paper, we study the critical behaviors in the non-Hermtian disorder Aubry-Andr\'{e} (DAA) model, and we assume the non-Hermiticity is introduced by the nonreciprocal hopping. We employ the localization length $\xi$, the inverse participation ratio ($\rm IPR$), and the real part of the energy gap between the first excited state and the ground state $\Delta E$ as the character quantities to describe the critical properties of the localization transition. By preforming the scaling analysis, the critical exponents of the non-Hermitian Anderson model and the non-Hermitian DAA model are obtained, and these critical exponents are different from their Hermitian counterparts, indicating the Hermitian and non-Hermitian disorder and DAA models belong to different universe classes. The critical exponents of non-Hermitian DAA model are remarkably different from both the pure non-Hermitian AA model and the non-Hermitian Anderson model, showing that disorder is a independent relevant direction at the non-Hermitian AA model. We further propose a hybrid scaling theory to describe the critical behavior in the overlapping critical region constituted by the critical regions of non-Hermitian DAA model and the non-Hermitian Anderson localization transition.