Drastic suppression of superconducting $T_{c}$ by anisotropic strain near a nematic quantum critical point

TL;DR

This study demonstrates that anisotropic strain can drastically suppress the superconducting transition temperature in Ba(Fe_{1-x}Co_{x})_{2}As_{2}, revealing a strain-tuned quantum phase transition near a nematic quantum critical point.

Contribution

It provides experimental evidence that anisotropic strain suppresses superconductivity and induces a quantum phase transition in an iron-based superconductor.

Findings

Superconducting T_c is rapidly suppressed by anisotropic strain.

Strain induces a superconductor-metal quantum phase transition.

Suppression of T_c is observed near a nematic quantum critical point.

Abstract

High temperature superconductivity emerges in the vicinity of competing strongly correlated phases. In the iron-based superconductor $Ba(Fe_{1-x}Co_{x})_{2}As_{2}$, the superconducting state shares the composition-temperature phase diagram with an electronic nematic phase and an antiferromagnetic phase that break the crystalline rotational symmetry. Symmetry considerations suggest that anisotropic strain can enhance these competing phases and thus suppress the superconductivity. Here we study the effect of anisotropic strain on the superconducting transition in single crystals of $Ba(Fe_{1-x}Co_{x})_{2}As_{2}$ through electrical transport, magnetic susceptibility, and x-ray diffraction measurements. We find that in the underdoped and near-optimally doped regions of the phase diagram, the superconducting critical temperature is rapidly suppressed by both compressive and tensile stress, and in the underdoped case this suppression is enough to induce a strain-tuned superconductor to metal quantum phase transition.