title: Singlet-triplet dispersion reveals additional frustration in the triangular-lattice dimer compound Ba3Mn2O8.
abstract: We present single crystal inelastic neutron scattering measurements of the S=1 dimerized quasi-two-dimensional antiferromagnet Ba(3)Mn(2)O(8). The singlet-triplet dispersion reveals nearest-neighbor and next-nearest-neighbor ferromagnetic interactions between adjacent bilayers that compete against each other. Although the interbilayer exchange is comparable to the intrabilayer exchange, this additional frustration reduces the effective coupling along the c axis and leads to a quasi-two-dimensional behavior. In addition, the obtained exchange values are able to reproduce the four critical fields in the phase diagram.
authors.affiliation: Neutron Scattering Science Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.
authors.forename: M B
authors.initials: MB
authors.lastname: Stone
authors.forename: M D
authors.initials: MD
authors.lastname: Lumsden
authors.forename: S
authors.initials: S
authors.lastname: Chang
authors.forename: E C
authors.initials: EC
authors.lastname: Samulon
authors.forename: C D
authors.initials: CD
authors.lastname: Batista
authors.forename: I R
authors.initials: IR
authors.lastname: Fisher