Strongly Gapped Spin-Wave Excitation in the Insulating Phase of NaOsO3
  NaOsO3 hosts a rare manifestation of a metal-insulator transition driven by magnetic correlations, placing the magnetic exchange interactions in a central role. We use resonant inelastic x-ray scattering to directly probe these magnetic exchange interactions. A dispersive and strongly gapped (58 meV) excitation is observed indicating appreciable spin-orbit coupling in this 5d3 system. The excitation is well described within a minimal model Hamiltonian with strong anisotropy and Heisenberg exchange (J1=J2=13.9 meV). The observed behavior places NaOsO3 on the boundary between localized and itinerant magnetism. 
S. Calder, J. G. Vale, N. Bogdanov, C. Donnerer, D. Pincini, M.   Moretti Sala, X. Liu, M. H. Upton, D. Casa, Y. G. Shi, Y. ...
cond-mat.str-el cond-mat.mtrl-sci