On the stability of polaronic superlattices in strongly coupled electron-phonon systems

TL;DR

This study explores how electron-phonon interactions and electronic correlations lead to polaronic superlattice formation in a 2D model, revealing self-localized carriers and charge orderings similar to nickel perovskites.

Contribution

It provides the first detailed numerical evidence of polaronic superlattice stability in a strongly coupled electron-phonon system with correlations.

Findings

Evidence of polaron self-localization in a charge-modulated superlattice.

Charge order similar to nickel perovskites observed.

Quantum phonon fluctuations included via Lanczos diagonalization.

Abstract

We investigate the interplay of electron-phonon (EP) coupling and strong electronic correlations in the frame of the two-dimensional (2D) Holstein t-J model (HtJM), focusing on polaronic ordering phenomena for the quarter-filled band case. The use of direct Lanczos diagonalization on finite lattices allows us to include the effects of quantum phonon fluctuations in the calculation of spin/charge structure factors and hole-phonon correlation functions. In the adiabatic strong coupling regime we found evidence for ``self-localization'' of polaronic carriers in a $(\pi,\pi)$ charge-modulated structure, a type of superlattice solidification reminiscent of those observed in the nickel perovskites $La_{2-x}Sr_{x}NiO_{4+y}$.