Magnetic field Controlled Anderson Delocalization in a Spinful Non-Hermitian Chain

TL;DR

This paper explores how an external magnetic field influences the competition between Anderson localization and the non-Hermitian skin effect in a disordered spinful 1D non-Hermitian chain, revealing magnetic control over localization transitions.

Contribution

It introduces the role of magnetic fields in manipulating localization phenomena in spinful non-Hermitian systems, demonstrating enhanced delocalization and crossover effects.

Findings

Magnetic field enhances AL to NHSE crossover.

Magnetic field facilitates Anderson delocalization in strong disorder.

Zeeman coupling suppresses effective disorder strength.

Abstract

Anderson localization (AL) and the non-Hermitian skin effect (NHSE) represent two paradigmatic localization phenomena driven, respectively, by disorder and non-Hermiticity. In one-dimensional (1D) non-Hermitian systems, these factors are known to compete and provide a smooth crossover between AL and NHSE upon parameter tuning. Here, we show that this interplay is fundamentally enriched in spinful systems, where an external magnetic field acts as an additional degree to manipulate the localization behavior. By investigating a disordered 1D spinful non-Hermitian chain, we demonstrate that under appropriately correlated disorder configurations across spin sectors, the magnetic field enhances the AL $\rightarrow$ NHSE crossover. Interestingly, this facilitates the Anderson delocalization transition even in strongly disordered systems where states would otherwise be Anderson localized. By analyzing the inverse participation ratio and the mean center of mass, we map the resulting triple interplay between disorder, non-Hermiticity, and the magnetic field strength, identifying regimes of Anderson localization and skin accumulation. We further reveal that this magnetic field driven delocalization phenomenon originates from an effective suppression of disorder strength via Zeeman-induced inter-chain coupling across the spin sectors.