Charge order in the incommensurate compounds $Sr\_{14-x}Ca\_xCu\_{24}O\_{41}$

TL;DR

This study uses ab-initio calculations to explore how incommensurate structural modulations affect the low energy physics and magnetic properties of Sr14-xCaxCu24O41 compounds, revealing their key role in electron localization and magnetic ordering.

Contribution

It provides a detailed analysis of the influence of structural modulations on electronic and magnetic properties using a $t-J+V$ model based on copper orbitals, highlighting their importance.

Findings

Structural modulations determine electron localization.

Modulations lead to dimer formation in x=0.

Anti-ferromagnetic order in x=13.6.

Abstract

The present paper studies, using ab-initio calculations, the influence of the incommensurate structural modulations on the low energy physics of the $Sr\_{14-x}Ca\_xCu\_{24}O\_{41}$ oxides. On-site, nearest-neighbor and next-nearest-neighbor effective parameters were computed within a $t-J+V$ model based on the copper magnetic orbitals. The structural modulations appear to be the key degree of freedom, responsible for the low energy properties such as the electron localization, the formation of dimers in the $x=0$ compound or the anti-ferromagnetic order in the $x=13.6$ compound.