Nonlinear Elastoresistivity Response in the $A_{1g}$ Symmetry Channel of the Iron Superconductor Ba(Fe$_{0.975}$Co$_{0.025}$)$_2$As$_2$

ORAL

Abstract

Elastoresistivity relates changes in resistance of a material to strains that it experiences. Previously we have shown how the $B_{2g}$ component of the elastoresistivity tensor is proportional to the nematic susceptibility, and hence can be used to infer a divergence of the nematic susceptibility approaching the tetragonal-to-orthorhombic structural phase transition in the Fe-based superconductors. In this talk I will introduce a new application of elastoresistance measurements for probing the resistivity response in the $A_{1g}$ symmetry channel. This is not a nematic symmetry; rather, it describes the isotropic response to strains that the material experiences. This technique was performed on a stereotypical iron based superconductor, Ba(Fe$_{0.975}$Co$_{0.025}$)$_2$As$_2$. We find that the response in the $A_{1g}$ channel is nonlinear with a quadratic elastoresistance coefficient that diverges close to the tetragonal to orthorhombic structural transition. I will explain the significance of these measurements and how they fit with our understanding from previous measurements of the $B_{2g}$ elastoresistance response.

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Authors

  • Johanna C. Palmstrom

    Stanford University and SLAC National Accelerator Laboratory, Stanford University

  • Jiun-Haw Chu

    Univ of Washington, University of Washington, Stanford University and University of Washington

  • Ian R. Fisher

    Department of Applied Physics, Stanford University, Stanford University, Stanford Univ, Geballe Laboratory for Advanced Materials and Department of Applied Physics, Stanford University, Stanford, CA 94305, Stanford University and SLAC National Accelerator Laboratory