Nematic quantum criticality in iron-based superconductors

Electronic nematicity refers to a self-organized electronic state that breaks rotational symmetry without long range translational order. In the iron-based superconductors, the nematic transition temperature can be continuously tuned by doping and pressure, which extrapolates to zero as the superconducting Tc is tuned to optimal. In this talk, I will present two striking phenomena associated with this putative nematic quantum critical point. First, we discovered that the superconductivity is extremely sensitive to the anisotropic strain near optimal doping – the Tc is reduced by five-fold under less than a percent anisotropic strain [1]. Second, using the combination of precision detwinning and elastoresistivity measurements, we found that the ratio between resistivity anisotropy and structural orthorhombicity within the nematic ordered phase enhances by fourfold as the doping approaches optimal, suggesting that the conduction electrons become increasingly sensitive to the lattice even as the nematic order is suppressed [2].

[1] P. Malinowski, Q. Jiang, J. Sanchez, Z.-Y. Liu, J. Mutch, P. Went, J. Liu, P. Ryan, J.-W. Kim, J.-H. Chu, “Drastic suppression of superconducting Tc by anisotropic strain near a nematic quantum critical point”, arXiv:1911.03390 (Nature Physics, 2020). [2] J.J. Sanchez, P. Malinowski, J. Mutch, J. Liu, J.-W. Kim, P. J. Ryan, J.-H. Chu, “The spontaneous elastoresistivity coefficient within the nematic ordered phase of iron pnictides”, arXiv:2006.09444v2.

Host: James Hamlin