A study of temperature dependent local atomic displacements in a Ba(Fe1-xCox)(2)As-2 superconductor


Hacisalihoglu M. Y. , Paris E., Joseph B., Simonelli L., Sato T. J. , Mizokawa T., ...Daha Fazla

PHYSICAL CHEMISTRY CHEMICAL PHYSICS, cilt.18, ss.9029-9035, 2016 (SCI İndekslerine Giren Dergi) identifier identifier identifier

  • Cilt numarası: 18 Konu: 13
  • Basım Tarihi: 2016
  • Doi Numarası: 10.1039/c5cp07985c
  • Dergi Adı: PHYSICAL CHEMISTRY CHEMICAL PHYSICS
  • Sayfa Sayıları: ss.9029-9035

Özet

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.