Singlet-triplet dispersion reveals additional frustration in the triangular-lattice dimer compound Ba3Mn2O8.
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.
Stone
M B
MB
Neutron Scattering Science Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.
Lumsden
M D
MD
Chang
S
S
Samulon
E C
EC
Batista
C D
CD
Fisher
I R
IR