title: Superconductivity. Nematic spin correlations in the tetragonal state of uniaxial-strained BaFe(2-x)Ni(x)As₂.
abstract: Understanding the microscopic origins of electronic phases in high-transition temperature (high-T(c)) superconductors is important for elucidating the mechanism of superconductivity. In the paramagnetic tetragonal phase of BaFe(2-x)T(x)As2 (where T is Co or Ni) iron pnictides, an in-plane resistivity anisotropy has been observed. Here, we use inelastic neutron scattering to show that low-energy spin excitations in these materials change from fourfold symmetric to twofold symmetric at temperatures corresponding to the onset of the in-plane resistivity anisotropy. Because resistivity and spin excitation anisotropies both vanish near optimal superconductivity, we conclude that they are likely intimately connected.
authors: Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
authors: Xingye
authors: X
authors: Lu
authors: Heinz Maier-Leibnitz Zentrum (MLZ), Technische Universität München, D-85748 Garching, Germany.
authors: J T
authors: JT
authors: Park
authors: Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
authors: Rui
authors: R
authors: Zhang
authors: Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
authors: Huiqian
authors: H
authors: Luo
authors: Department of Physics and Astronomy, Rice University, Houston, TX 77005, USA.
authors: Andriy H
authors: AH
authors: Nevidomskyy
authors: Department of Physics and Astronomy, Rice University, Houston, TX 77005, USA.
authors: Qimiao
authors: Q
authors: Si
authors: Department of Physics and Astronomy, Rice University, Houston, TX 77005, USA.Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China. pdai@rice.edu.
authors: Pengcheng
authors: P
authors: Dai