Inelastic neutron scattering determination of the spin Hamiltonian for BaCdVO(PO4)2

Abstract

Single crystal inelastic neutron scattering is used to study spin-wave excitations in the fully polarized state of the frustrated quantum ferroantiferromagnet BaCdVO(PO4)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 eight 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.