Microstructural evolution throughout the structural transition in 1111 oxypnictides

2012/04/05 by A. Martinelli, A. Palenzona, M. Putti +1 · 20 citations
Chemistry · Materials Science · Physics and Astronomy · #Advanced Condensed Matter Physics #Anisotropy #Chemistry #Condensed matter physics #Crystal structure #Crystallography #Iron-based superconductors research #Lattice (music) #Liquid crystal #Materials science #Optics #Orthorhombic crystal system #Phase transition #Physics #Rare-earth and actinide compounds #Tetragonal crystal system #cond-mat.supr-con

paper · pdf · doi:10.1103/physrevb.85.224534

published in Physical Review B 85(22) (American Physical Society)

arxiv created 2012/04/05 · openalex publication_date 2012/06/28 · arxiv updated 2015/06/04 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05

Abstract

The microstructural evolution throughout the first-order tetragonal-to-orthorhombic structural transition is analyzed by powder diffraction analysis for two different systems belonging to the class of compounds referred to as 1111 oxypnictides: (La_1\ensuremath-yY_y)FeAsO and SmFeAs(O_1\ensuremath-xF_x). Both systems are characterized by similar behavior: On cooling, microstrain along the tetragonal hh0 direction takes place and increases as the temperature is decreased. Just above the structural transition, microstrain reaches its maximum value and then is abruptly suppressed by symmetry breaking. No volume discontinuity throughout the first-order transition is observed, and a group-subgroup relationship holds between the tetragonal and the orthorhombic structures, thus suggesting that orbital ordering drives symmetry breaking. Microstrain reflects a distribution of lattice parameters in the tetragonal phase and explains the occurrence of anisotropic properties commonly attributed to nematic correlations; in this scenario, the nematic behavior is induced by the tendency towards ordering of Fe orbitals.

Citations

• Competing magnetic ground states in nonsuperconducting Ba(Fe1−xCrx)2As2as seen via neutron diffraction
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• Crystal structure and phase transitions across the metal-superconductor boundary in theSmFeAsO1−xFx(0≤x≤0.20)family
• Recent advances in magnetic structure determination by neutron powder diffraction
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• The effect of internal pressure on the tetragonal to monoclinic structural phase transition in ReOFeAs: the case of NdOFeAs
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• Origin of the 150-K Anomaly in LaFeAsO: Competing Antiferromagnetic Interactions, Frustration, and a Structural Phase Transition