Determination of the Nature of the Tetragonal to Orthorhombic Phase Transition in SrFe_2As_2 by Measurement of the Local Order Parameter

Abstract

SrFe2As2 is the end-member for a series of iron-pnictide superconductors and has a tetragonal-to-orthorhombic phase transition near 200 K. Previous macroscopic measurements to determine the nature of the transition gave seemingly inconsistent results so we use electron microscopy to monitor the local order parameter showing that the transformation is first order and that the orthorhombic phase grows as needle domains. This suggests the transition occurs via the passage of transformation dislocations, explaining the apparent inconsistencies. This mechanism may be common to similar transitions.

4 pages, 4 figures submitted to Physical Review Letters. Supplementary information can be found at http://cook.msm.cam.ac.uk/~supp_info/ An extra sentence in the second last paragraph and reference 16 has been added

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Cited by in corpus (7)

• The Puzzle of High Temperature Superconductivity in Layered Iron Pnictides and Chalcogenides
• The phase diagrams of iron-based superconductors: theory and experiments
• In-plane anisotropy of electrical resistivity in the strain-detwinned SrFe2As2
• Phase transitions and iron-ordered moment form factor in LaFeAsO
• Distinct high-T transitions in underdoped Ba${}_{1-x}$K${}_x$Fe${}_2$As${}_2$
• Quantum Criticality in the 122 Iron Pnictide Superconductors Emerging from Orbital-Selective Mottness
• Anisotropic magnetoelastic coupling in single-crystalline CeFeAsO as seen via high-resolution x-ray diffraction