CIRCULAR-DICHROISM IN HIGH-TEMPERATURE SUPERCONDUCTORS - A CHARACTERISTIC OF BROKEN SPACE-INVERSION SYMMETRY

The circular optical dichroism recently observed in a number of high-temperature superconductors has been commonly interpreted in terms of violation of both time-reversal invariance and space-inversion symmetry (the magnetoelectric effect). It is shown, however, that in view of numerous experimental observations of various piezoelectric or ferroelectric phenomena in these superconductors, the effect could be naturally interpreted in terms of a linear space dispersion of the dielectric tensor of a dissipative medium that lacks a center of inversion. Both bulk and surface contributions to the effect are discussed.