We report a comprehensive neutron scattering study of low energy magnetic excitations in the breathing pyrochlore helimagnetic CuOSeO. Fully documenting the four lowest energy magnetic modes that leave the ferrimagnetic configuration of the "strong tetrahedra" intact ( meV), we find gapless quadratic dispersion at the point for energies above 0.2 meV, two doublets separated by 1.6(2) meV at the point, and a bounded continuum at the point. Our constrained rigid spin cluster model relates these features to Dzyaloshinskii-Moriya (DM) interactions and the incommensurate helical ground state. Combining conventional spin wave theory with a spin cluster form factor accurately reproduces the measured equal time structure factor through multiple Brillouin zones. An effective spin Hamiltonian describing complex anisotropic intercluster interactions is obtained.
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| http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7919739 | PMC |
| http://dx.doi.org/10.1103/PhysRevB.101.144411 | DOI Listing |
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