Online video supplement for Phys. Rev. B 79, 180508(R) (2009)

10.1103/PhysRevB.79.180508

http://arxiv.org/abs/0904.2337

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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

Ames Laboratory and Department of Physics & Astronomy, Iowa State University, Ames, Iowa 50011

Submitted: 15 April 2009

Abstract

The parent compounds of recently discovered iron-arsenide superconductors, AFe₂As₂ 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 um. 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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In the videos a transition from orthorhombic to tetragonal and back to orthorhombic structure is shown upon warming from below T_SM to above T_SM and back to below T_SM. Each frame width is about 0.3 mm. If you have questions regarding this page and its content, please contact Ruslan Prozorov: prozorov @ ameslab.gov

CaFe₂As₂

SrFe₂As₂

BaFe₂As₂

last updated 15 April 2009