Anisotropic atomic displacements, local orthorhombicity and anomalous local magnetic moment in Ba<sub>0.6</sub>K<sub>0.4</sub>Fe<sub>2</sub>As<sub>2</sub> superconductor

Creative Commons License

Tortora L., Tomassucci G., Pugliese G. M., Hacisalihoglu M. Y., Simonelli L., Marini C., ...More

PHYSICAL CHEMISTRY CHEMICAL PHYSICS, vol.26, no.34, pp.22454-22462, 2024 (SCI-Expanded, Scopus) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 26 Issue: 34
  • Publication Date: 2024
  • Doi Number: 10.1039/d4cp02345e
  • Journal Name: PHYSICAL CHEMISTRY CHEMICAL PHYSICS
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.22454-22462
  • Ankara University Affiliated: No

Abstract

We have investigated the in-plane local structure of the Ba0.6K0.4Fe2As2 superconductor by polarized Fe K-edge extended X-ray absorption fine structure (EXAFS) measurements with temperature. The near neighbor bond distances and their stiffness, measured by polarized EXAFS in two orthogonal directions, are different suggesting in-plane anisotropy of the atomic displacements and local orthorhombicity in the title system. The X-ray absorption near edge structure (XANES) spectra reveal anisotropy of valence electronic structure that changes anomalously below similar to 100 K. The local iron magnetic moment, measured by Fe K beta X-ray emission spectroscopy (XES), increases below the anomalous temperature and shows a decrease in the vicinity of the superconducting transition temperature (T-c similar to 36 K). The results provide a clear evidence of coupled local lattice, electronic and magnetic degrees of freedom to induce possible nematic fluctuations in an optimally hole doped iron-based superconductor.