Abstract
Elastic neutron-scattering studies of single-crystal LaFeAsO reveal that upon cooling, an onset of the tetragonal (T)-to-orthorhombic (O) structural transition occurs at TS ≈156 K, and it exhibits a sharp transition at TP ≈148 K. We argue that in the temperature range T S to TP, T and O structures may dynamically coexist possibly due to nematic spin correlations recently proposed for the iron pnictides, and we attribute TP to the formation of long-range O domains from the finite local precursors. The antiferromagnetic structure emerges at TN ≈140 K, with the iron moment direction along the O a axis. We extract the iron magnetic form factor and use the tabulated 〈 j0 〉 of Fe, Fe2+, and Fe3+ to obtain a magnetic moment size of ∼0.8 μB at 9.5 K.
Original language | English |
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Article number | 064409 |
Journal | Physical Review B - Condensed Matter and Materials Physics |
Volume | 82 |
Issue number | 6 |
DOIs | |
State | Published - Aug 9 2010 |
Externally published | Yes |