Magnetic susceptibility in quasi one-dimensional Ba2V3O9: chain segmentation versus the staggered field effect

TL;DR

This study investigates the origin of the Curie-like upturn in magnetic susceptibility of Ba2V3O9, concluding that chain segmentation due to broken bonds, rather than the staggered field effect, explains the experimental observations.

Contribution

The paper demonstrates that chain segmentation from broken magnetic bonds accounts for the susceptibility behavior, challenging the common attribution to the staggered field mechanism.

Findings

Chain segmentation explains the low-temperature susceptibility upturn.

Approximately 1% broken bonds reproduce experimental data.

Staggered field effects are too small to account for observations.

Abstract

A pronounced Curie-like upturn of the magnetic susceptibility chi(T) of the quasi one-dimensional spin chain compound Ba2V3O9 has been found recently. Frequently this is taken as a signature for a staggered field mechanism due to the presence of g-factor anisotropy and Dzyaloshinskii-Moriya interaction. We calculate this contribution within a realistic structure of vanadium 3d- and oxygen 2p-orbitals and conclude that this mechanism is far too small to explain experimental results. We propose that the Curie term is rather due to a segmentation of spin chains caused by broken magnetic bonds which leads to uncompensated S=1/2 spins of segments with odd numbers of spins. Using a finite-temperature Lanczos method we calculate their effective moment and show that ~1% of broken magnetic bonds is sufficient to reproduce the anomalous low-T behavior of chi(T) in Ba2V3O9.