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Persistent URL http://purl.org/net/epubs/work/50811
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Record Id 50811
Title Spin waves and magnetic exchange interactions in CaFe2As2
Abstract Antiferromagnetism is relevant to high-temperature (high-Tc) superconductivity because copper oxide and iron arsenide superconductors arise from electron- or hole-doping of their antiferromagnetic parent compounds. There are two broad classes of explanation for antiferromagnetism: in the 'local moment' picture, appropriate for the insulating copper oxides, antiferromagnetic interactions are well described by a Heisenberg Hamiltonian; whereas in the 'itinerant model', suitable for metallic chromium, antiferromagnetic order arises from quasiparticle excitations of a nested Fermi surface. There has been contradictory evidence regarding the microscopic origin of the antiferromagnetic order in iron arsenide materials with some favouring a localized picture and others supporting an itinerant point of view. More importantly, there has not even been agreement about the simplest effective ground-state Hamiltonian necessary to describe the antiferromagnetic order. Here, we use inelastic neutron scattering to map spin-wave excitations in CaFe2As2, a parent compound of the iron arsenide family of superconductors. We find that the spin waves in the entire Brillouin zone can be described by an effective three-dimensional local-moment Heisenberg Hamiltonian, but the large in-plane anisotropy cannot. Therefore, magnetism in the parent compounds of iron arsenide superconductors is neither purely local nor purely itinerant, rather it is a complicated mix of the two.
Organisation ISIS , ISIS-MERLIN , STFC
Keywords Physics
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Language English (EN)
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Journal Article Nature 5 (2009): 555-560. doi:10.1038/nphys1336 2009