Effects of annealing and doping concentration on the critical current density and superconducting properties of $Ba(Fe_{1-x}Co_x)_2As_2$ and $Ba_{0.5}Sr_{0.5}(Fe_{1-y}Co_y)_2As_2$

ORAL

Abstract

We report on the study we have made in order to better understand the intrinsic nature of superconductivity and pinning mechanisms in $Ba(Fe_{1-x}Co_x)_2As_2$ with various cobalt concentration and in $Ba_{0.5}Sr_{0.5}(Fe_{1-y}Co_{y})_2$. The critical current density $J_c$(as functions of temperature, and applied magnetic field) for different x values of 0.04, 0.08, and 0.15 (underdoped, optimally doped and overdoped respectively) is determined magnetically. From the $J_c (H)$ analysis, we see that $J_c$ slowly decays with respect to H in all the samples. We also found that $J_c$ in the annealed compared to the as-grown sample is enhanced in the underdoped and the optimally doped $Ba(Fe_{1-x}Co_x)_2As_2$ while there is no difference in the overdoped $Ba(Fe_{1-x}Co_x)_2As_2$ and the $Ba_{0.5}Sr_{0.5}(Fe_{1-y}Co_{y})_2$. Analysis of the $J_c$(T) data shows a weak pinning feature rather than correlated pinning. The pinning force $F_p$ as a function of the irreversible field $H_{irr}$ is also analyzed to gain further insights into the pinning mechanism.

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Authors

  • A.O. Ijaduola

    University of North Georgia

  • J.K. Hwang

    Western Kentucky University, University of Pardubice, Francis Marion University, Clemson University Professor, Francis Marion University Professor, Undergraduate Administrator, Oak Ridge National Laboratory, Oak Ridge, Tennessee, Austin Peay State University, University Strenwarte-Muenchen, Seoul National University, Gatton Academy for Science and Mathematics, Alabama A\&M University, Cygnus, Center for Nanophase Materials Science at Oak Ridge National Laboratory, Vanderbilt University, Fisk Univ, 2Cornell High Energy Synchrotron Source, Cornell University, Ithaca, NY, NOVA Center, Western Kentucky University, Department of Physics, Florida A\&M University, Tallahassee, FL-32307, Correlated Electron Materials Group, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6061 USA, Department of Electrical Engineering and Computer Science, Vanderbilt University, Nashville, TN 37235, USA, Department of Electrical and Computer Engineering, University of Rochester, Rochester, NY 14627, USA, The Institute of Optics, University of Rochester, Rochester, NY 14627, USA, Universidade Estadual Paulista (UNESP), Clark Atlanta University, Deapartment of Physics \& Astronomy, Georgia State University, USA, Department of Electrical and Computer Engineering, McGill University, Montreal, QC H3A 2A7, Canada, Oak Ridge National Laboratory, University of South Alabama, Samford University, University of Rochester, University of North Carolina, Chapel Hill, Sandia National Laboratories, New Mexico State University, University of Tennessee Space Institute, Shanghai Jiao Tong University, Shanghai, China, University of Leeds, Leeds, UK, Georgia State University, Atlanta GA, University of Alabama at Birmingham, National High Magnetic Field Laboratory, Prairie View A\&M University, Brookhaven National Laboratory, University of Southern Indiana, Center for Nanophase Materials Sciences at Oak Ridge National Laboratory, JINR(Dubna), Tsinghua Univ., LBNL, Vanderbilt Univ., Vanderbilt Univ./Univ. of Tennessee, Knoxville, Vanderbilt Univ./Univ. of Kentucky, GANIL, Vanderbilt Univ./Union Univ., JINR, ORAU, Tsinghua University, LNBL

  • J.K. Hwang

    Western Kentucky University, University of Pardubice, Francis Marion University, Clemson University Professor, Francis Marion University Professor, Undergraduate Administrator, Oak Ridge National Laboratory, Oak Ridge, Tennessee, Austin Peay State University, University Strenwarte-Muenchen, Seoul National University, Gatton Academy for Science and Mathematics, Alabama A\&M University, Cygnus, Center for Nanophase Materials Science at Oak Ridge National Laboratory, Vanderbilt University, Fisk Univ, 2Cornell High Energy Synchrotron Source, Cornell University, Ithaca, NY, NOVA Center, Western Kentucky University, Department of Physics, Florida A\&M University, Tallahassee, FL-32307, Correlated Electron Materials Group, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6061 USA, Department of Electrical Engineering and Computer Science, Vanderbilt University, Nashville, TN 37235, USA, Department of Electrical and Computer Engineering, University of Rochester, Rochester, NY 14627, USA, The Institute of Optics, University of Rochester, Rochester, NY 14627, USA, Universidade Estadual Paulista (UNESP), Clark Atlanta University, Deapartment of Physics \& Astronomy, Georgia State University, USA, Department of Electrical and Computer Engineering, McGill University, Montreal, QC H3A 2A7, Canada, Oak Ridge National Laboratory, University of South Alabama, Samford University, University of Rochester, University of North Carolina, Chapel Hill, Sandia National Laboratories, New Mexico State University, University of Tennessee Space Institute, Shanghai Jiao Tong University, Shanghai, China, University of Leeds, Leeds, UK, Georgia State University, Atlanta GA, University of Alabama at Birmingham, National High Magnetic Field Laboratory, Prairie View A\&M University, Brookhaven National Laboratory, University of Southern Indiana, Center for Nanophase Materials Sciences at Oak Ridge National Laboratory, JINR(Dubna), Tsinghua Univ., LBNL, Vanderbilt Univ., Vanderbilt Univ./Univ. of Tennessee, Knoxville, Vanderbilt Univ./Univ. of Kentucky, GANIL, Vanderbilt Univ./Union Univ., JINR, ORAU, Tsinghua University, LNBL

  • J.K. Hwang

    Western Kentucky University, University of Pardubice, Francis Marion University, Clemson University Professor, Francis Marion University Professor, Undergraduate Administrator, Oak Ridge National Laboratory, Oak Ridge, Tennessee, Austin Peay State University, University Strenwarte-Muenchen, Seoul National University, Gatton Academy for Science and Mathematics, Alabama A\&M University, Cygnus, Center for Nanophase Materials Science at Oak Ridge National Laboratory, Vanderbilt University, Fisk Univ, 2Cornell High Energy Synchrotron Source, Cornell University, Ithaca, NY, NOVA Center, Western Kentucky University, Department of Physics, Florida A\&M University, Tallahassee, FL-32307, Correlated Electron Materials Group, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6061 USA, Department of Electrical Engineering and Computer Science, Vanderbilt University, Nashville, TN 37235, USA, Department of Electrical and Computer Engineering, University of Rochester, Rochester, NY 14627, USA, The Institute of Optics, University of Rochester, Rochester, NY 14627, USA, Universidade Estadual Paulista (UNESP), Clark Atlanta University, Deapartment of Physics \& Astronomy, Georgia State University, USA, Department of Electrical and Computer Engineering, McGill University, Montreal, QC H3A 2A7, Canada, Oak Ridge National Laboratory, University of South Alabama, Samford University, University of Rochester, University of North Carolina, Chapel Hill, Sandia National Laboratories, New Mexico State University, University of Tennessee Space Institute, Shanghai Jiao Tong University, Shanghai, China, University of Leeds, Leeds, UK, Georgia State University, Atlanta GA, University of Alabama at Birmingham, National High Magnetic Field Laboratory, Prairie View A\&M University, Brookhaven National Laboratory, University of Southern Indiana, Center for Nanophase Materials Sciences at Oak Ridge National Laboratory, JINR(Dubna), Tsinghua Univ., LBNL, Vanderbilt Univ., Vanderbilt Univ./Univ. of Tennessee, Knoxville, Vanderbilt Univ./Univ. of Kentucky, GANIL, Vanderbilt Univ./Union Univ., JINR, ORAU, Tsinghua University, LNBL

  • J.K. Hwang

    Western Kentucky University, University of Pardubice, Francis Marion University, Clemson University Professor, Francis Marion University Professor, Undergraduate Administrator, Oak Ridge National Laboratory, Oak Ridge, Tennessee, Austin Peay State University, University Strenwarte-Muenchen, Seoul National University, Gatton Academy for Science and Mathematics, Alabama A\&M University, Cygnus, Center for Nanophase Materials Science at Oak Ridge National Laboratory, Vanderbilt University, Fisk Univ, 2Cornell High Energy Synchrotron Source, Cornell University, Ithaca, NY, NOVA Center, Western Kentucky University, Department of Physics, Florida A\&M University, Tallahassee, FL-32307, Correlated Electron Materials Group, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6061 USA, Department of Electrical Engineering and Computer Science, Vanderbilt University, Nashville, TN 37235, USA, Department of Electrical and Computer Engineering, University of Rochester, Rochester, NY 14627, USA, The Institute of Optics, University of Rochester, Rochester, NY 14627, USA, Universidade Estadual Paulista (UNESP), Clark Atlanta University, Deapartment of Physics \& Astronomy, Georgia State University, USA, Department of Electrical and Computer Engineering, McGill University, Montreal, QC H3A 2A7, Canada, Oak Ridge National Laboratory, University of South Alabama, Samford University, University of Rochester, University of North Carolina, Chapel Hill, Sandia National Laboratories, New Mexico State University, University of Tennessee Space Institute, Shanghai Jiao Tong University, Shanghai, China, University of Leeds, Leeds, UK, Georgia State University, Atlanta GA, University of Alabama at Birmingham, National High Magnetic Field Laboratory, Prairie View A\&M University, Brookhaven National Laboratory, University of Southern Indiana, Center for Nanophase Materials Sciences at Oak Ridge National Laboratory, JINR(Dubna), Tsinghua Univ., LBNL, Vanderbilt Univ., Vanderbilt Univ./Univ. of Tennessee, Knoxville, Vanderbilt Univ./Univ. of Kentucky, GANIL, Vanderbilt Univ./Union Univ., JINR, ORAU, Tsinghua University, LNBL