Abstract
We use neutron scattering to study temperature-dependent spin excitations in insulating antiferromagnetic (AF) RbFeSe. In the low-temperature AF state, spin waves can be accurately described by a local moment Heisenberg Hamiltonian. On warming to around the Néel temperature of K, low-energy ( meV) paramagnetic spin excitations form Lorentzian-like quasielastic peaks centered at the AF wave vectors associated with spin waves, while high-energy ( meV) spin excitations become heavily damped. Upon further warming to above the structural distortion temperature of K, the entire paramagnetic excitations become overdamped. These results suggest that AF RbFeSe is not a copper-oxide–like Mott insulator and has less electron correlations compared with metallic iron pnictides and iron chalcogenides.
- Received 8 October 2012
DOI:https://doi.org/10.1103/PhysRevB.87.064409
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