Incommensurate spin density modulation in a copper-oxide chain compound with commensurate charge order

TL;DR

This study uses neutron diffraction to reveal complex magnetic ordering in Na$_8$Cu$_5$O$_{10}$, showing incommensurate spin density modulation influenced by interchain interactions in a charge-ordered copper-oxide chain compound.

Contribution

It provides the first detailed magnetic structure analysis of Na$_8$Cu$_5$O$_{10}$, highlighting incommensurate spin density modulation linked to interchain exchange interactions.

Findings

Long-range collinear magnetic order below 23 K

Incommensurate spin density modulation observed

Charge order persists well above room temperature

Abstract

Neutron diffraction has been used to determine the magnetic structure of Na$_8$Cu$_5$O$_{10}$, a stoichiometric compound containing chains based on edge-sharing CuO$_4$ plaquettes. The chains are doped with 2/5 hole per Cu site and exhibit long-range commensurate charge order with an onset well above room temperature. Below $T_N = 23$ K, the neutron data indicate long-range collinear magnetic order with a spin density modulation whose propagation vector is commensurate along and incommensurate perpendicular to the chains. Competing interchain exchange interactions are discussed as a possible origin of the incommensurate magnetic order.