title: Ubiquitous signatures of nematic quantum criticality in optimally doped Fe-based superconductors.
abstract: A key actor in the conventional theory of superconductivity is the induced interaction between electrons mediated by the exchange of virtual collective fluctuations (phonons in the case of conventional s-wave superconductors). Other collective modes that can play the same role, especially spin fluctuations, have been widely discussed in the context of high-temperature and heavy Fermion superconductors. The strength of such collective fluctuations is measured by the associated susceptibility. Here we use differential elastoresistance measurements from five optimally doped iron-based superconductors to show that divergent nematic susceptibility appears to be a generic feature in the optimal doping regime of these materials. This observation motivates consideration of the effects of nematic fluctuations on the superconducting pairing interaction in this family of compounds and possibly beyond.
authors.affiliation: Stanford Institute of Energy and Materials Science, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park 94025, CA 94305, USA. Department of Material Science and Engineering and Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA 94305, USA.
authors.forename: Hsueh-Hui
authors.initials: HH
authors.lastname: Kuo
authors.affiliation: Stanford Institute of Energy and Materials Science, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park 94025, CA 94305, USA. Department of Applied Physics and Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA 94305, USA.
authors.forename: Jiun-Haw
authors.initials: JH
authors.lastname: Chu
authors.affiliation: Stanford Institute of Energy and Materials Science, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park 94025, CA 94305, USA. Department of Applied Physics and Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA 94305, USA.
authors.forename: Johanna C
authors.initials: JC
authors.lastname: Palmstrom
authors.affiliation: Stanford Institute of Energy and Materials Science, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park 94025, CA 94305, USA. Department of Physics and Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA 94305, USA.
authors.forename: Steven A
authors.initials: SA
authors.lastname: Kivelson
authors.affiliation: Stanford Institute of Energy and Materials Science, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park 94025, CA 94305, USA. Department of Applied Physics and Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA 94305, USA.
authors.forename: Ian R
authors.initials: IR
authors.lastname: Fisher