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

Date
2013-11-01
Authors
Khan, Suffian
Alam, Aftab
Johnson, Duane
Johnson, Duane
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Ames Laboratory
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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 nanotwins (twin nuclei), and spin excitations proposed and/or observed. These nanoscale defects have a 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. Nanotwins explain features in measured pair distribution functions so should be considered when analyzing scattering data. All these defects can be weakly mobile and/or can have fluctuations that lower assessed “ordered” moments from longer spatial and/or time averaging and should be considered directly.

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<p>This article is from Phys. Rev. B <strong>88</strong>, 184515 (2013), doi:<a href="http://dx.doi.org/10.1103/PhysRevB.88.184515" target="_blank">10.1103/PhysRevB.88.184515</a>. Posted with permission.</p>
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Materials Science and Engineering
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