Dispersive magnetic excitations in the S=1 antiferromagnet Ba3Mn2O8
Abstract
We present powder inelastic neutron scattering measurements of the S=1 dimerized antiferromagnet Ba3Mn2O8. The T=1.4 K magnetic spectrum exhibits a spin-gap of ≈ 1.0 meV and a dispersive spectrum with a bandwidth of approximately 1.5 meV. Comparison to coupled dimer models describe the dispersion and scattering intensity accurately and determine the exchange constants in Ba3Mn2O8. The wave vector dependent scattering intensity confirms the proposed S=1 dimer bond. Temperature dependent measurements of the magnetic excitations indicate the presence of both singlet-triplet and thermally activated triplet-quintet excitations.
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