Spin subdiffusion in disordered Hubbard chain

TL;DR

This paper investigates the anomalous subdiffusive spin transport in a disordered Hubbard chain, deriving an effective model that links spin dynamics to disorder-induced localization effects.

Contribution

It introduces a new effective spin model explaining subdiffusion in disordered Hubbard systems, connecting spin exchange interactions to Anderson localization.

Findings

Spins are delocalized while charges are localized under strong disorder.

Subdiffusive transport arises from a singular distribution of spin exchange interactions.

The subdiffusion exponent depends on the Anderson localization length and electron density.

Abstract

We derive and study the effective spin model that explains the anomalous spin dynamics in the one-dimensional Hubbard model with strong potential disorder. Assuming that charges are localized, we show that spins are delocalized and their subdiffusive transport originates from a singular random distribution of spin exchange interactions. The exponent relevant for the subdiffusion is determined by the Anderson localization length and the density of electrons. While the analytical derivations are valid for low particle density, numerical results for the full model reveal a qualitative agreement up to half-filling.