Disorder effects in multiorbital $s_{\pm}$-wave superconductors: Implications for Zn-doped BaFe$_2$As$_2$ compounds

ORAL

Abstract

Recent experiments on Zn-doped 122-type iron pnictides, Ba(Fe$_{1-x-y}$Co$_y$Zn$_x$)$_2$As$_2$, are challenging our understanding of electron doping the 122s and the interplay between doping and impurity scattering. To resolve this enigma, we investigate the disorder effects of nonmagnetic Zn impurities on various properties of the system in the $s_{\pm}$-wave pairing state. The BdG is solved based on a minimal two-orbital model with an extended range of impurity concentrations. With increasing Zn concentration the density of states shows a gradual filling of the gap, revealing pair breaking effect. Both the averaged superconducting order parameter and superfluid density are dramatically suppressed towards the dirty limit, indicating the violation of the Anderson theorem and breakdown of the AG theory for impurity-averaged Green's functions. The superconductivity is fully suppressed close to the critical impurity concentration of $n_{\mathrm{imp}}\approx 10\%$, in agreement with recent experiments.

–

Authors

  • Hua Chen

    ZIMP, Zhejiang University, 310027, China

  • Yuan-Yen Tai

    Department of Physics and Texas Center for Superconductivity, University of Houston, Univ of Houston Dept of Physics, Department of Physics and Texas Center for Superconductivity, University of Houston, Houston, Texas 77204, USA

  • C.S. Ting

    Univ of Houston Dept of Physics, Department of Physics and Texas Center for Superconductivity, University of Houston, Houston, Texas 77204, USA

  • Matthias J. Graf

    Los Alamos National Laboratory, Los Alamos National Lab, Theoretical Division and Center for Nonlinear Studies, LANL, Los Alamos, New Mexico 87545, USA

  • Jianhui Dai

    Department of Physics, Hangzhou Normal University, 310036, China

  • Jian-Xin Zhu

    Los Alamos National Laboratory, Theoretical Division and Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA, Theoretical Division and Center for Integrated Technologies, Los Alamos National Laboratory, Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, Los Alamos National Lab, Theoretical Division and Center for Nonlinear Studies, LANL, Los Alamos, New Mexico 87545, USA, Los Alamos Natl Lab