Time-reversal symmetry breaking versus superstructure
  One of the mysteries of modern condenced-matter physics is the nature of the pseudogap state of the superconducting cuprates. Kaminski et al.1 claimed to have observed signatures of time-reversal symmetry breaking in the pseudogap regime in underdoped Bi2Sr2CaCu2O8+d (Bi2212). Here we argue that the observed dichroism is due to the 5x1 superstructure replica of the electronic bands and therefore cannot be considered as evidence for the spontaneous time-reversal symmetry breaking in cuprates. 
S. V. Borisenko, A. A. Kordyuk, A. Koitzsch, M. Knupfer, J. Fink