2009/02/06 by Dirk Johrendt, Rainer Pöttgen, Rainer Poettgen
Chemistry · Materials Science · Physics and Astronomy · #Anisotropy #Antiferromagnetism #Chemistry #Condensed matter physics #Crystal structure #Crystallography #Doping #Hyperfine structure #Iron-based superconductors research #Magnetism #Materials science #Mössbauer spectroscopy #Physics #Rare-earth and actinide compounds #Superconductivity #Tetragonal crystal system #cond-mat.str-el #cond-mat.supr-con
paper · pdf · doi:10.1016/j.physc.2009.03.018
23 pages, 12 figures, submitted to Physica C, special issue on Fe-pnictides
arxiv created 2009/02/06 · openalex publication_date 2009/03/20 · arxiv updated 2015/05/12 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
BaFe2As2 is the parent compound of the '122' iron arsenide superconductors and crystallizes with the tetragonal ThCr2Si2 type structure, space group I4/mmm. A spin density wave transition at 140 K is accompanied by a symmetry reduction to space group Fmmm and simultaneously by antiferromagnetic ordering. Hole-doping induces superconductivity in Ba1-xKxFe2As2 with a maximum Tc of 38 K at x = 0.4. The upper critical fields approach 75 T with rather small anisotropy of Hc2. At low potassium concentrations (x <= 0.2), superconductivity apparently co-exists with the orthorhombic distorted and magnetically ordered phase. At doping levels x >= 0.3, the structural distortion and antiferromagnetic ordering is completely suppressed and the Tc is maximized. No magnetically ordered domains could be detected in optimally doped Ba1-xKxFe2As2 (x >= 0.3) by 57Fe-Moessbauer spectroscopy in contrast muSR results obtained with single crystals. The magnetic hyperfine interactions investigated by 57Fe Moessbauer spectroscopy are discussed and compared to the ZrCuSiAs-type materials.