We have studied the local structure of a Ba(Fe1-xCox)(2)As-2 superconductor using temperature dependent extended X-ray absorption fine structure (EXAFS) measurements. Polarized EXAFS at the Fe K-edge on an optimally doped (x = 0.06) single crystal has permitted us to determine atomic displacements across the superconducting transition temperature (T-c). The Fe-As bondlength hardly shows any change with temperature; however, the Fe-Fe sublattice reveals a sharp anomaly across T-c, indicated by a significant drop in mean square relative displacements, similar to the one known for cuprates and A15-type superconductors. We have also found a large atomic disorder around the substituted Co, revealed by polarized Co K-edge EXAFS measurements. The Co-Fe/Co bonds are more flexible than the Fe-Fe bonds with the As-height in Co-containing tetrahedra being larger than the one in FeAs4. The results suggest that the local Fe-Fe bondlength fluctuations and the atomic disorder in this sub-lattice should have some important role in the superconductivity of Ba(Fe1-xCox)(2)As-2 pnictides.
A study of temperature dependent local atomic displacements in a Ba(Fe1−xCox)2As2superconductor / Hacisalihoglu, M. Y.; Paris, Eugenio; Joseph, B.; Simonelli, L.; Sato, T. J.; Mizokawa, T.; Saini, Naurang Lal. - In: PHYSICAL CHEMISTRY CHEMICAL PHYSICS. - ISSN 1463-9076. - 18:13(2016), pp. 9029-9035. [10.1039/C5CP07985C]
A study of temperature dependent local atomic displacements in a Ba(Fe1−xCox)2As2superconductor
Hacisalihoglu, M. Y.;PARIS, EUGENIO;SAINI, Naurang Lal
2016
Abstract
We have studied the local structure of a Ba(Fe1-xCox)(2)As-2 superconductor using temperature dependent extended X-ray absorption fine structure (EXAFS) measurements. Polarized EXAFS at the Fe K-edge on an optimally doped (x = 0.06) single crystal has permitted us to determine atomic displacements across the superconducting transition temperature (T-c). The Fe-As bondlength hardly shows any change with temperature; however, the Fe-Fe sublattice reveals a sharp anomaly across T-c, indicated by a significant drop in mean square relative displacements, similar to the one known for cuprates and A15-type superconductors. We have also found a large atomic disorder around the substituted Co, revealed by polarized Co K-edge EXAFS measurements. The Co-Fe/Co bonds are more flexible than the Fe-Fe bonds with the As-height in Co-containing tetrahedra being larger than the one in FeAs4. The results suggest that the local Fe-Fe bondlength fluctuations and the atomic disorder in this sub-lattice should have some important role in the superconductivity of Ba(Fe1-xCox)(2)As-2 pnictides.File | Dimensione | Formato | |
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