Anisotropic three-dimensional magnetism in CaFe2As2

Inelastic neutron scattering measurements of the magnetic excitations in CaFe2As2 indicate that the spin wave velocity in the Fe layers is exceptionally large and similar in magnitude to the cuprates. However, the spin wave velocity perpendicular to the layers is at least half as large that in the layer, so that the magnetism is more appropriately categorized as anisotropic three-dimensional, in contrast to the two-dimensional cuprates. Exchange constants derived from band structure calculations predict spin wave velocities that are consistent with the experimental data.
neutron diffraction, spin dynamics, spin waves, magnetic superconductors, iron alloys, exchange interactions (electron), calcium alloys, atomic force microscopy, anisotropic three-dimensional magnetism, magnetic excitations, inelastic neutron scattering, spin wave velocity, arsenic alloys, antiferromagnetism, ab initio calculations, two-dimensional cuprates, exchange constants, band structure calculations, CaFe2As2
Physical Review Letters 28 Nov. 2008, vol.101, no.22, 227205 (4 pp.)