On the absence of a spiral magnetic order in Li2CuO2 with one-dimensional CuO2 ribbon chains

TL;DR

This study uses first principles calculations to investigate why Li2CuO2 does not display a spiral magnetic order, revealing that nearly degenerate states and interchain interactions favor a collinear magnetic structure.

Contribution

It demonstrates that the collinear magnetic structure in Li2CuO2 arises from order-by-disorder effects due to interchain interactions, explaining the absence of spiral order.

Findings

Collinear magnetic structure is nearly degenerate with spiral states.

Next-nearest-neighbor interchain interactions influence magnetic stability.

Order-by-disorder mechanism explains magnetic ordering in Li2CuO2.

Abstract

On the basis of first principles density functional theory electronic structure calculations as well as classical spin analysis, we explored why the magnetic oxide Li2CuO2, consisting of CuO2 ribbon chains made up of edge-sharing CuO4 squares, does not exhibit a spiral-magnetic order. Our work shows that, due to the next-nearest-neighbor interchain interactions, the observed collinear magnetic structure becomes only slightly less stable than the spin-spiral ground state, and many states become nearly degenerate in energy with the observed collinear structure. This suggests that the collinear magnetic structure of Li2CuO2 is a consequence of order-by-disorder induced by next-nearest-neighbor interchain interactions.