Linear Spin Wave Theory Applied to NaNiO_2

NaNiO_2 and LiNiO_2 are isomorphic quantum magnets. The magnetic behavior of LiNiO_2 has been the focus of a range of speculations over the past two decades, however, there is currently no consensus regarding the magnetic behavior of this material. Interestingly, while experiments performed on LiNiO_2 to probe its magnetic structure have shown an absence of long range order, recent inelastic neutron scattering measurements indicate that the low energy excitations of NaNiO_2 can be described by spin waves. We believe that a clear understanding of the magnetic behavior of NaNiO_2 will lead to insights with respect to LiNiO_2. We apply linear spin wave theory to NaNiO_2 and obtain the dynamic structure factor. The result is found to be in reasonable agreement with the dynamic structure factor measured by inelastic neutron scattering experiments.