Abstract
The anisotropy of the magnetic excitations in BaFeAs was studied by polarized inelastic neutron scattering, which allows one to separate the components of the magnetic response. Despite the in-plane orientation of the static ordered moment, we find the in-plane polarized magnons to exhibit a larger gap than the out-of-plane polarized ones, indicating very strong single-ion anisotropy within the layers. It costs more energy to rotate a spin within the orthorhombic a-b plane than to rotate it perpendicular to the FeAs layers.
- Received 11 January 2012
DOI:https://doi.org/10.1103/PhysRevB.86.060410
©2012 American Physical Society