Symmetry considerations for detection of time-reversal breaking phases in cuprates by x-ray diffraction and absorption

Time-reversal and inversion breaking in the pseudogap region of the cuprate compounds have been proposed and detected by means of angle-resolved photoemission spectroscopy in the compound Bi-2212. Given the implication of the effect in the physics of the cuprate superconductors, it is important to check the conclusions through quite independent experimental techniques. We show how time-reversal and inversion breaking may be revealed in the cuprates through resonant x-ray scattering and through nonreciprocal or magnetochiral dichroism.