Anisotropy of incommensurate magnetic excitations in slightly overdoped Ba0.5K0.5Fe2As2 probed by polarized inelastic neutron scattering experiments.

Polarized neutron scattering experiments on the slightly overdoped superconductor Ba0.5K0.5Fe2As2 reveal broad magnetic resonance scattering peaking at approximately 15 meV. In spite of doping far beyond the suppression of magnetic order, this compound exhibits dispersive and anisotropic magnetic excitations. At energies below the resonance maximum, magnetic correlations polarized parallel to the layers but perpendicular to the propagation vector are reduced by a factor of 2 compared to those in the two orthogonal directions; in contrast, correlations at the peak maximum are isotropic. [ABSTRACT FROM AUTHOR]