Quasi one-dimensional magnetism driven by unusual orbital ordering in CuSb2O6

TL;DR

This study uncovers a unique orbital ordering in CuSb2O6 that leads to quasi-one-dimensional magnetism, contrasting with typical cuprates, and explains recent experimental observations.

Contribution

It reveals an unusual half-filled 3d-(3z^2-r^2) orbital in CuSb2O6 caused by Coulomb interactions, leading to novel magnetic properties.

Findings

Unusual orbital ordering in CuSb2O6 identified

Quasi-one-dimensional magnetic behavior observed

Consistent explanation for thermodynamical and neutron data provided

Abstract

Essentially all undoped cuprates exhibit a quasi-planar, fourfold Cu-O coordination responsible for the magnetically active antibonding 3d-(x^2-y^2)-like state. Here, we present an electronic structure study for CuSb2O6 that reveals, in contrast, a half-filled 3d-(3z^2-r^2) orbital. This hitherto unobserved ground state originates from a competition of in- and out-of-plaquette orbitals where the strong Coulomb repulsion drives the surprising and unique orbital ordering. This, in turn, gives rise to an unexpected quasi one-dimensional magnetic behavior. Our results provide a consistent explanation of recent thermodynamical and neutron diffraction measurements.