Abstract
The duality between the localized and itinerant nature of magnetism in -electron systems has been a long-standing puzzle. Here, we report inelastic neutron scattering measurements, which reveal both local and itinerant aspects of magnetism in a single-crystalline system of . In the antiferromagnetic state, we observe a broad continuum of diffuse magnetic scattering with a resonancelike gap of and the surprising absence of coherent spin waves, suggestive of itinerant magnetism. While the gap closes above the Néel temperature, strong dynamic spin correlations persist to a high temperature. Nevertheless, the size and temperature dependence of the total magnetic spectral weight can be well described by a local moment with . Furthermore, polarized neutron measurements reveal that the magnetic fluctuations are mostly transverse, with little or none of the longitudinal component expected for itinerant moments. These results suggest that a dual description of local and itinerant magnetism is required to understand and, by extension, other systems, in general.
- Received 5 October 2017
DOI:https://doi.org/10.1103/PhysRevLett.121.057201
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