Hole-depletion of ladders in Sr$_{14}$Cu$_{24}$O$_{41}$ induced by correlation effects

TL;DR

This study combines advanced spectroscopy and electronic structure calculations to reveal how correlation effects influence hole distribution in Sr$_{14}$Cu$_{24}$O$_{41}$, showing a preference for chain sites and explaining phase diagram cross-over.

Contribution

It demonstrates that correlations and magnetic ordering drive hole localization on chains over ladders, challenging previous semi-empirical models.

Findings

Correlations favor chain hole attraction.

Holes prefer leg sites over rung sites.

Explains 1D-2D phase cross-over in related compounds.

Abstract

The hole distribution in Sr$_{14}$Cu$_{24}$O$_{41}$ is studied by low temperature polarization dependent O K Near-Edge X-ray Absorption Fine Structure measurements and state of the art electronic structure calculations that include core-hole and correlation effects in a mean-field approach. Contrary to all previous analysis, based on semi-empirical models, we show that correlations and antiferromagnetic ordering favor the strong chain hole-attraction. For the remaining small number of holes accommodated on ladders, leg-sites are preferred to rung-sites. The small hole affinity of rung-sites explains naturally the 1D - 2D cross-over in the phase diagram of (La,Y,Sr,Ca)$_{14}$Cu$_{24}$O$_{41}$