The parent compound of the Fe oxypnictide superconductor, LaFeAsO, has been studied by pulsed neutron powder inelastic scattering measurement. The inelastic scattering intensity along the Q-axis at T = 140K exhibits a prominent asymmetric peak ascribed to the (π, π, I) magnetic rod, suggesting the two-dimensionality of the spin density wave above the magnetic transition temperature. It persists even in the tetragonal phase up to room temperature, which is well above the magnetic transition temperature, corresponding to two antiferromagnetic sublattices or domains with a strong effective antiferromagnetic interaction J 2 between next-nearest-neighbour Fe magnetic moments in a single Fe square lattice.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)