Wigner crystallization in Na(3)Cu(2)O(4) and Na(8)Cu(5)O(10) chain compounds

TL;DR

This paper reports the synthesis and analysis of novel chain compounds Na(3)Cu(2)O(4) and Na(8)Cu(5)O(10), identifying them as one-dimensional Wigner lattices with charge order driven by Coulomb interactions.

Contribution

It introduces new chain compounds as Wigner lattices and distinguishes classical charge order from quantum charge-density waves using experimental data.

Findings

Identification of Na(3)Cu(2)O(4) and Na(8)Cu(5)O(10) as Wigner lattices.

Charge order determined by Coulomb interactions and hole count.

Differentiation between classical Wigner lattice and quantum 4k_F CDW.

Abstract

We report the synthesis of novel edge-sharing chain systems Na(3)Cu(2)O(4) and Na(8)Cu(5)O(10), which form insulating states with commensurate charge order. We identify these systems as one-dimensional Wigner lattices, where the charge order is determined by long-range Coulomb interaction and the number of holes in the d-shell of Cu. Our interpretation is supported by X-ray structure data as well as by an analysis of magnetic susceptibility and specific heat data. Remarkably, due to large second neighbor Cu-Cu hopping, these systems allow for a distinction between the (classical) Wigner lattice and the 4k_F charge-density wave of quantum mechanical origin.