Dispersive magnetic excitations in the S=1 antiferromagnet Ba3Mn2O8

Journal Article · Tue Jan 01 04:00:00 EST 2008 · Physical Review B

DOI:https://doi.org/10.1103/PhysRevB.77.134406· OSTI ID:931135

Stone, Matthew B ^[1]; Lumsden, Mark D ^[1]; Qiu, Y. ^[2]; Samulon, Eric C ^[3]; Batista, C. D. ^[4]; Fisher, Ian R ^[3]

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1. ORNL
2. National Institute of Standards and Technology (NIST)
3. Stanford University
4. 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 Laboratory (ORNL); High Flux Isotope Reactor; Spallation Neutron Source
• Sponsoring Organization: SC USDOE - Office of Science (SC)
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 931135
• Journal Information: Physical Review B, Journal Name: Physical Review B Journal Issue: 13 Vol. 77; ISSN PRBMDO; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ANTIFERROMAGNETIC MATERIALS
DIMERS
NEUTRONS
SCATTERING
VECTORS