2009/11/10 by D. S. Inosov, Tetyana Shapoval, T. Shapoval +20 · 1 citation
Materials Science · Physics and Astronomy · #Iron-based superconductors research #Physics of Superconductivity and Magnetism #Superconductivity in MgB2 and Alloys #cond-mat.dis-nn #cond-mat.supr-con
paper · pdf · doi:10.1103/physrevb.81.014513
published as Phys. Rev. B 81, 014513 (2010) · 11 pages, 6 figures
arxiv created 2009/11/10 · openalex publication_date 2010/01/19 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
The disordered flux line lattice in single crystals of the slightly overdoped BaFe_2\ensuremath-xCoxAs2 (x=0.19, Tc=23 K) superconductor is studied by magnetization measurements, small-angle neutron scattering, and magnetic force microscopy (MFM). In the whole range of magnetic fields up to 9 T, vortex pinning precludes the formation of an ordered Abrikosov lattice. Instead, a vitreous vortex phase (vortex glass) with a short-range hexagonal order is observed. Statistical processing of MFM data sets lets us directly measure its radial and angular distribution functions and extract the radial correlation length \ensuremathζ. In contrast to predictions of the collective pinning model, no increase in the correlated volume with the applied field is observed. Instead, we find that \ensuremathζ decreases as (1.3\ifmmode±\else\textpm\fi0.1)R1\ensuremath∝H^\ensuremath-1/2 over four decades of the applied magnetic field, where R1 is the radius of the first coordination shell of the vortex lattice. Such universal scaling of \ensuremathζ implies that the vortex pinning in iron arsenides remains strong even in the absence of static magnetism. This result is consistent with all the real and reciprocal-space vortex-lattice measurements in overdoped as-grown BaFe_2\ensuremath-xCoxAs2 published to date and is thus sample independent. The failure of the collective pinning model suggests that the vortices remain in the single-vortex pinning limit even in high-magnetic fields up to 9 T.