Anisotropic impurity states, quasiparticle scattering and nematic transport in underdoped Ca(Fe 1− x Co x ) 2 As 2

When CaFe2As2 is lightly doped with Co an electronic liquid-crystalline state emerges, which becomes the ‘parent’ state of high-temperature superconductivity in this ferropnictide. A spectroscopic imaging study shows that the ‘nematic’ order is likely to be an artefact of the doping itself.