Spin Waves and Magnetic Correlations in the Multiferroic Sr0.56Ba0.44MnO3

Neutron diffraction and inelastic scattering measurements have been carried out on a polycrystalline sample of ferroelectric Sr$_{\mathrm{0.56}}$Ba$_{\mathrm{0.44}}$MnO$_{\mathrm{3}}$ (T$_{\mathrm{F\thinspace }}=$ 350 K) using the BT-7 and SPINS triple-axis spectrometers. The system orders antiferromagnetically at 197 K with an order parameter that varies smoothly with temperature. Inelastic measurements at base temperature reveal an energy gap of 4.6(5) meV, with a continuous distribution of magnetic scattering above the gap that exhibits a weak peak at 7.5 meV. The top of the magnon band was measured to be 43(1) meV. The data were modeled with a simple nearest-neighbor exchange$ J$ and the measured anisotropy gap, which was powder-averaged and fit to the data to yield an exchange constant $J=$4.8(2) meV. Above T$_{\mathrm{N}}$ strong correlations persist, consistent with the determined exchange as the scattering broadens in wave vector. Replace this text with your abstract body.