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arXiv · 1303.4024

Low-energy, planar magnetic defects in BaFe2As2: nanotwins, twins, antiphase and domain boundaries

S. N. Khan·Aftab Alam·D. D. Johnson
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Abstract

In BaFe2As2, structural and magnetic planar defects begin to proliferate below the structural phase transition, affecting descriptions of magnetism and superconductivity. We study using density-functional theory the stability and magnetic properties of competing antiphase and domain boundaries, twins and isolated $nano$twins (twin nuclei) - spin excitations proposed and/or observed. These nanoscale defects have very low surface energy ($22$-$210$~$m$Jm$^{-2}$), with twins favorable to the mesoscale. Defects exhibit smaller moments confined near their boundaries -- making a uniform-moment picture inappropriate for long-range magnetic order in real samples. {\it{Nano}}twins explain features in measured pair distribution functions, so should be considered when analyzing scattering data. All these defects can be weakly mobile and/or have fluctuations that lower assessed "ordered" moments from longer spatial and/or time averaging, and should be considered directly.

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S. N. Khan, Aftab Alam, D. D. Johnson. 2013-03-16. Low-energy, planar magnetic defects in BaFe2As2: nanotwins, twins, antiphase and domain boundaries. https://doi.org/10.1103/physrevb.88.184515

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