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arXiv · 0904.2337

Direct imaging of the structural domains in iron pnictides AFe2As2 (A = Ca, Sr, Ba)

M. A. Tanatar·A. Kreyssig·S. Nandi·N. Ni·S. L. Bud'ko·P. C. Canfield·A. I. Goldman·R. Prozorov
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Abstract

The parent compounds of recently discovered iron-arsenide superconductors, $A$Fe$_2$As$_2$ with alkaline earth $A$=Ca, Sr, Ba, undergo simultaneous structural and magnetic phase transitions at a temperature $T_{SM}$. Using a combination of polarized light microscopy and spatially resolved high-energy synchrotron X-ray diffraction we show that the orthorhombic distortion leads to the formation of 45$^o$-type structural domains in all parent compounds. Domains penetrate through the sample thickness in the $c$- direction and are not affected by crystal defects such as growth terraces. The domains form regular stripe patterns in the plane with a characteristic dimension of 10 to 50 $μm$. The direction of the stripes is fixed with respect to the tetragonal (100) and (010) directions but can change by 90$^o$ on thermal cycling through the transition. This domain pattern may have profound implications for intrinsic disorder and anisotropy of iron arsenides.

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M. A. Tanatar, A. Kreyssig, S. Nandi, N. Ni, S. L. Bud'ko, P. C. Canfield, A. I. Goldman, R. Prozorov. 2009-04-15. Direct imaging of the structural domains in iron pnictides AFe2As2 (A = Ca, Sr, Ba). https://arxiv.org/abs/0904.2337

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