Dispersive magnetic excitations in the S=1 antiferromagnet Ba3Mn2O8
- ORNL
- National Institute of Standards and Technology (NIST)
- Stanford University
- Los Alamos National Laboratory (LANL)
We present powder inelastic neutron scattering measurements of the $S=1$ dimerized antiferromagnet Ba$$_3$$Mn$$_2$$O$$_8$$. The $T=1.4$~K~magnetic spectrum exhibits a spin-gap of $$\Delta = 0.9$$~meV and a dispersive spectrum with a bandwidth of approximately $1.74$~meV. Comparison to coupled dimer models describe the dispersion and scattering intensity accurately and determine the exchange constants in Ba$$_3$$Mn$$_2$$O$$_8$$. Interdimer exchange between triangular lattice dimer bilayers in Ba$$_3$$Mn$$_2$$O$$_8$$ is two orders of magnitude weaker than intradimer exchange. Ba$$_3$$Mn$$_2$$O$$_8$$ is thus a quasi-two-dimensional frustrated bilayer triangular lattice of $S=1$ dimers. 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.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). High Flux Isotope Reactor (HFIR); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source (SNS)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- DE-AC05-00OR22725
- OSTI ID:
- 931135
- Journal Information:
- Physical Review B, Vol. 77, Issue 13; ISSN 0163-1829
- Country of Publication:
- United States
- Language:
- English
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