title: Nematic Crossover in BaFe(2)As(2) under Uniaxial Stress.
abstract: Raman scattering can detect spontaneous point-group symmetry breaking without resorting to single-domain samples. Here, we use this technique to study BaFe(2)As(2), the parent compound of the "122" Fe-based superconductors. We show that an applied compression along the Fe-Fe direction, which is commonly used to produce untwinned orthorhombic samples, changes the structural phase transition at temperature T(s) into a crossover that spans a considerable temperature range above T(s). Even in crystals that are not subject to any applied force, a distribution of substantial residual stress remains, which may explain phenomena that are seemingly indicative of symmetry breaking above T(s). Our results are consistent with an onset of spontaneous nematicity only below T(s).
authors.affiliation: International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China.
authors.forename: Xiao
authors.initials: X
authors.lastname: Ren
authors.affiliation: International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China.
authors.forename: Lian
authors.initials: L
authors.lastname: Duan
authors.affiliation: International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China.
authors.forename: Yuwen
authors.initials: Y
authors.lastname: Hu
authors.affiliation: International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China.
authors.forename: Jiarui
authors.initials: J
authors.lastname: Li
authors.affiliation: Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA.
authors.forename: Rui
authors.initials: R
authors.lastname: Zhang
authors.affiliation: Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
authors.forename: Huiqian
authors.initials: H
authors.lastname: Luo
authors.affiliation: Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA.
authors.forename: Pengcheng
authors.initials: P
authors.lastname: Dai
authors.affiliation: International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China.|Collaborative Innovation Center of Quantum Matter, Beijing 100871, China.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Li