Circular Dichroism in the Angle-Resolved Photoemission Spectrum of the High-Temperature Bi2Sr2CaCu2O8+δ Superconductor: Can These Measurements Be Interpreted as Evidence for Time-Reversal Symmetry Breaking?

We report first-principles computations of the angle-resolved photoemission response with circularly polarized light in Bi2Sr2CaCu2O8+delta for the purpose of delineating contributions to the circular dichroism resulting from distortions and modulations of the crystal lattice. Comparison with available experimental results shows that the measured circular dichroism from antinodal mirror planes is reproduced in quantitative detail in calculations employing the average orthorhombic crystal structure. We thus conclude that the existing angle-resolved photoemission measurements can be understood essentially within the framework of the conventional picture, without the need to invoke unconventional mechanisms.