Muon Spin Relaxation Study of Ba(Fe$_{0.93}$Co$_{0.07})_{2}$As$_{2}$

ORAL

Abstract

We have performed muon spin relaxation ($\mu $SR) measurements of superconducting Ba(Fe$_{0.93}$Co$_{0.07})_{2}$As$_{2}$. Zero field measurements show that static magnetism is absent for this Co concentration. In the mixed state, we observe a well-formed vortex lattice which results in an anisotropic $\mu $SR lineshape. We have fit the spectra to a microscopic model for the vortex state to obtain the magnetic field penetration depth. The penetration depth is about 2000{\AA} in low (200G) fields and increases with applied field. The temperature dependence of the superfluid density is well described by a power law; behaviour which is consistent with gap nodes, substantial gap anisotropy or multi-band superconductivity. Research at McMaster University is supported by NSERC and CIFAR. Work at the Ames Laboratory was supported by the Department of Energy, Basic Energy Sciences under Contract No. DE-AC02-07CH11358.

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Authors

  • Graeme Luke

    • McMaster University

  • A.A. Aczel

    • McMaster University

  • J. P. Carlo

    • Columbia University
    • Department of Physics, Columbia University, New York, NY

  • T. Goko

    • TRIUMF

  • T.J. Williams

    • McMaster University

  • N. Ni

    • Ames Laboratory

  • S.L. Bud'ko

    • Ames Laboratory and Iowa State University
    • Ames Laboratory and Physics Department and Astronomy, Iowa State University, Ames, IA
    • Ames Laboratory
    • Ames Laboratory, US DOE and Iowa State University
    • Ames Laboratory/Iowa State University
    • Ames Laboratory/Department of Physics and Astronomy
    • Ames laboratory

  • P.C. Canfield

    • Ames Laboratory and Department of Physics and Astronomy, Iowa State Univeristy, Ames, Iowa 50011
    • Ames Laboratory and Iowa State University
    • Ames Laboratory and Physics Department and Astronomy, Iowa State University, Ames, IA
    • Ames Laboratory
    • Ames Laboratory, US DOE and Iowa State University
    • Ames Laboratory/Department of Physics and Astronomy
    • Ames Lab / Iowa State University
    • Ames Laboratory/Iowa State University

  • Y.J. Uemura

    • Columbia University