Phase transitions and iron-ordered moment form factor in LaFeAsO
|Title||Phase transitions and iron-ordered moment form factor in LaFeAsO|
|Publication Type||Journal Article|
|Year of Publication||2010|
|Authors||Li HF, Tian W, Yan JQ, Zarestky JL, McCallum RW, Lograsso TA, Vaknin D|
|Journal Title||Physical Review B|
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 T-S approximate to 156 K, and it exhibits a sharp transition at T-P approximate to 148 K. We argue that in the temperature range T-S to T-P, T and O structures may dynamically coexist possibly due to nematic spin correlations recently proposed for the iron pnictides, and we attribute T-P to the formation of long-range O domains from the finite local precursors. The antiferromagnetic structure emerges at T-N approximate to 140 K, with the iron moment direction along the O a axis. We extract the iron magnetic form factor and use the tabulated < j(0)> of Fe, Fe2+, and Fe3+ to obtain a magnetic moment size of similar to 0.8 mu B at 9.5 K.
|URL||<Go to ISI>://000280758300004|