Magnetic properties of NaV2O5, a one-dimensional spin 1/2 antiferromagnet with finite chains

TL;DR

This study investigates the magnetic susceptibility of NaV₂O₅, revealing it behaves as a one-dimensional spin-1/2 antiferromagnetic chain with finite length, and develops a model to explain low-temperature deviations from standard behavior.

Contribution

The paper introduces a finite chain susceptibility model for NaV₂O₅, providing insights into its magnetic interactions and implications for similar compounds like CaV₄O₉.

Findings

High-temperature susceptibility consistent with spin 1/2 chains and J=529 K.

Finite chain model explains low-temperature susceptibility deviations.

Suggests a large next-nearest-neighbour exchange integral in related compounds.

Abstract

We have performed measurements of the magnetic susceptibility of NaV$_2$O$_5$ between 2 and 400 K. The high temperature part is typical of spin 1/2 chains with a nearest--neighbour antiferromagnetic exchange integral $J$ of 529 K. We develop a model for the susceptibility of a system with finite chains to account for the low temperature part of the data, which cannot be fitted by a standard Curie-Weiss term. These results suggest that the next nearest--neighbour exchange integral $J_2$ in CaV$_4$O$_9$ should be of the order of 500 K because, like $J$ in NaV$_2$O$_5$, it corresponds to corner sharing VO$_5$ square pyramids.