Itinerant magnetic excitations in antiferromagnetic CaFe2As2

Abstract
Neutron scattering measurements of the magnetic excitations in single crystals of antiferromagnetic CaFe2As2 reveal steeply dispersive and well-defined spin waves up to an energy of ~100 meV. Magnetic excitations above 100 meV and up to the maximum energy of 200 meV are however broader in energy and momentum than the experimental resolution. While the low energy modes can be fit to a Heisenberg model, the total spectrum cannot be described as arising from excitations of a local moment system. Ab initio calculations of the dynamic magnetic susceptibility suggest that the high energy behavior is dominated by the damping of spin waves by particle-hole excitations.
Description
Keywords
neutron diffraction, magnetic susceptibility, magnetic moments, iron compounds, itinerant magnetic excitations;, neutron scattering, single crystals, spin waves, Heisenberg model, local moment system, calcium compounds, band model of magnetism, antiferromagnetic materials, ab initio calculations, dynamic magnetic susceptibility, particle-hole excitations, CaFe2As2
Citation
Physical Review Letters 8 May 2009, vol.102, no.18, 187206 (4 pp