Quasiparticle interference in antiferromagnetic parent compounds of   Fe-based superconductors
  Recently reported quasiparticle interference imaging in underdoped Ca(Fe{1-x}Co{x})_2As{2} shows pronounced C{2} asymmetry that is interpreted as an indication of an electronic nematic phase with a unidirectional electron band, dispersive predominantly along the $b$-axis of this orthorhombic material. On the other hand, even more recent transport measurements on untwinned samples show near isotropy of the resistivity in the $ab$ plane, with slightly larger conductivity along a (and not b). We show that in fact both sets of data are consistent with the calculated ab initio Fermi surfaces, which has a decisively broken C_{4}, and yet similar Fermi velocity in both directions. This reconciles completely the apparent contradiction between the conclusions of the STM and the transport experiments. 
I.I. Mazin, Simon A.J. Kimber, and Dimitri N. Argyriou
cond-mat.supr-con