Inelastic neutron scattering determination of the spin Hamiltonian for BaCdVO(PO$_4$)$_2$

TL;DR

This study uses inelastic neutron scattering to precisely determine the spin Hamiltonian of BaCdVO(PO$_4$)$_2$, revealing a more accurate model of its magnetic interactions than previous powder-based analyses.

Contribution

It provides the first comprehensive, quantitative spin Hamiltonian for BaCdVO(PO$_4$)$_2$ based on single crystal data, improving understanding of its magnetic properties.

Findings

All 8 exchange constants determined from neutron scattering data.

The model significantly differs from previous powder-based assumptions.

Establishes a definitive, quantitative magnetic interaction model for the material.

Abstract

Single crystal inelastic neutron scattering is used to study spin wave excitations in the fully polarized state of the frustrated quantum ferro-antiferromagnet BaCdVO(PO$_4$)$_2$. The data analysis is based on a Heisenberg spin Hamiltonian that includes as many distinct nearest-neighbor and next-nearest neighbor interactions as allowed by crystal symmetry. All 8 such exchange constants are obtained in a simultaneous fit to over 150 scans across the dispersion manifold. This establishes a definitive quantitative model of this material. It turns out to be substantially different from the one assumed in numerous previous studies based on powder experiments.