Ren, XiaoDuan, LianHu, YuwenLi, JiaruiZhang, RuiLuo, HuiqianDai, PengchengLi, Yuan2016-06-102016-06-102015Ren, Xiao, Duan, Lian, Hu, Yuwen, et al.. "Nematic Crossover in BaFe2As2 under Uniaxial Stress." <i>Physical Review Letters,</i> 115, no. 19 (2015) American Physical Society: 197002. http://dx.doi.org/10.1103/PhysRevLett.115.197002.https://hdl.handle.net/1911/90485Raman scattering can detect spontaneous point-group symmetry breaking without resorting to single-domain samples. Here, we use this technique to study BaFe2As2, 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 Ts into a crossover that spans a considerable temperature range above Ts. 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 Ts. Our results are consistent with an onset of spontaneous nematicity only below Ts.engArticle is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.Journal articlehttp://dx.doi.org/10.1103/PhysRevLett.115.197002