The unusual electronic structure of the "pseudo-ladder" compound CaCu2O3

TL;DR

This study investigates the electronic structure of CaCu2O3, revealing an unusual hole distribution and strong interlayer exchange that differ from typical cuprates, impacting its magnetic properties.

Contribution

It provides new experimental and theoretical insights into the unoccupied electronic structure of CaCu2O3, highlighting deviations from standard cuprate models.

Findings

Large number of holes in orbitals parallel to interlayer direction

Deviation from standard pd-sigma cuprate picture

Strong interlayer exchange affects magnetic properties

Abstract

Experimental and theoretical studies of the unoccupied electronic structure of CaCu2O3 single crystals have been performed using polarization-dependent x-ray absorption spectroscopy and band structure calculations. The measured hole distribution shows an unusual large number of holes in orbitals parallel to the interlayer direction which is in agreement with the theoretical analysis. CaCu2O3 deviates significantly from the standard pd-sigma cuprate picture. The corresponding strong interlayer exchange is responsible for the missing spin gap generic for other two-leg ladder cuprates.