The fate of the spin polaron in the 1D antiferromagnets

TL;DR

This paper investigates the stability of the spin polaron in 1D antiferromagnets using a t-J model, revealing that it collapses due to magnon interactions, and is only stable at a specific interaction strength.

Contribution

It provides a detailed numerical analysis showing the collapse of the spin polaron in 1D and identifies the conditions under which it remains stable, offering new insights into 1D antiferromagnet spectra.

Findings

Spin polaron collapses in 1D due to magnon interactions.

Stable spin polaron exists only at a specific magnon-magnon interaction strength.

Results suggest the spin polaron is the relevant quasiparticle in realistic 1D materials.

Abstract

The stability of the spin polaron quasiparticle, well established in studies of a single hole in the 2D antiferromagnets, is investigated in the 1D antiferromagnets using a t-J model. We perform an exact slave fermion transformation to the holon-magnon basis, and diagonalize numerically the resulting model in the presence of a single hole. We demonstrate that the spin polaron collapses - and the spin-charge separation takes over - due to the specific role played by the magnon-magnon interactions and the magnon hard-core constraint in the 1D t-J model. Moreover, we prove that the spin polaron is stable for any strength of the magnon-magnon interaction other than the unique value found in a 1D antiferromagnet with the continuous symmetry of the spin interactions. Fine-tuning to this unique value is extremely unlikely to occur in quasi-1D antiferromagnets, therefore the spin polaron is the stable quasiparticle of realistic 1D materials. Our results lead to a new interpretation of the ARPES spectra of quasi-1D antiferromagnets in the spin polaron language.