Ab Initio Calculation of Spin Gap Behavior in CaV4O9

TL;DR

This paper uses ab initio density functional calculations to model the magnetic interactions in CaV4O9, accurately predicting its spin-gap behavior and matching experimental data.

Contribution

It introduces a DF-based self-consistent atomic deformation model that explains the small nearest neighbor coupling and accurately predicts spin-gap behavior.

Findings

Predicted spin-gap behavior matches experimental results

Model accurately reproduces susceptibility and triplet dispersion

Second neighbor exchange coupling dominates in CaV4O9

Abstract

Second neighbor dominated exchange coupling in CaV4O9 has been obtained from ab initio density functional (DF) calculations. A DF-based self-consistent atomic deformation model reveals that the nearest neighbor coupling is small due to strong cancellation among the various superexchange processes. Exact diagonalization of the predicted Heisenberg model yields spin-gap behavior in good agreement with experiment. The model is refined by fitting to the experimental susceptibility. The resulting model agrees very well with the experimental susceptibility and triplet dispersion.