Magnetic imaging of vortices and inhomogeneity in Ba(Fe,Co)$_2$As$_2$ by magnetic force microscopy

ORAL

Abstract

Single crystals of BaFe$_{2-x}$Co$_x$As$_2$ synthesized by FeAs flux method were studied by variable temperature magnetic force microscopy (VT-MFM). The nominal Co doping concentrations range from underdoped region (x$\sim$0.1) to optimum doped region (x$\sim$0.2) of the superconducting dome. Sharp superconducting transitions ($\sim$1K) indicate good sample quality. Individual Abrikosov vortices were visualized by VT-MFM below Tc at low magnetic field. The temperature dependence of vortex configuration indicates a strong pinning effect, which is supported by Bean-model behavior\footnote{C.P. Bean, PRL, 8, 250 (1962).} observed at high magnetic field. Results of magnetic inhomogeneity of underdoped samples will be discussed.

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Authors

  • Weida Wu

  • S. Park

    • Rutgers Center for Emergent Materials and Dept. of Physics \& Astronomy, Rutgers University

  • Linjun Li

  • Yongkang Li

  • Hang Chen

  • Guanghan Cao

  • Zhuan Xu

    • Department of Physics Zhejiang University, Hangzhou 310027 China
    • Zhejiang University