Anisotropic atomic displacements, local orthorhombicity and anomalous local magnetic moment in Ba0.6K0.4Fe2As2 superconductor

Tortora L., Tomassucci G., Pugliese G., HACISALİHOĞLU 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, Chemical Abstracts Core, Chimica, Communication Abstracts, Compendex, INSPEC, MEDLINE
  • Page Numbers: pp.22454-22462
  • Recep Tayyip Erdoğan University Affiliated: Yes

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 ∼100 K. The local iron magnetic moment, measured by Fe Kβ X-ray emission spectroscopy (XES), increases below the anomalous temperature and shows a decrease in the vicinity of the superconducting transition temperature (Tc ∼ 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.