2016/08/31 by A. Fente, William R. Meier, W. R. Meier +10
Chemistry · Materials Science · Mathematics · Physics and Astronomy · #Chemistry #Condensed matter physics #Iron-based superconductors research #Mathematical analysis #Mathematics #Physical chemistry #Physics #Physics of Superconductivity and Magnetism #Rare-earth and actinide compounds #Sign (mathematics) #Stoichiometry #Superconductivity #Thermodynamics #Vortex #cond-mat.supr-con
paper · pdf · doi:10.1103/physrevb.97.134501
published as Phys. Rev. B 97, 134501 (2018) · 7 figures
arxiv created 2017/12/19 · openalex created_date 2018/01/05 · openalex publication_date 2018/04/02 · arxiv updated 2018/04/04 · openalex updated_date 2026/08/05
We use a scanning tunneling microscope to study the superconducting density of states and vortex lattice of single crystals of CaKFe4As4. This material has a critical temperature of Tc=35 K, one of the highest among stoichiometric iron based superconductors (FeBSCs), and is comparable to Tc found near optimal doping in other FeBSCs. We observe quasiparticle scattering from defects with a pattern related to interband scattering between zone centered hole sheets. We measure the tunneling conductance in vortex cores and find a peak due to Caroli--de Gennes--Matricon bound states. The peak is located above the Fermi level, showing that CaKFe4As4 is a clean superconductor with vortex core bound states close to the so-called extreme quantum limit. We identify locations where the superconducting order parameter is strongly suppressed due to pair breaking. Vortices are pinned at these locations, and the length scale of the suppression of the order parameter is of order of the vortex core size. As a consequence, the vortex lattice is disordered up to 8 T.