FIG. 2.

(a) depicts the Rashba-type band structure of CH₃NH₃PbI₃ along k_x(k_y = 0, k_z = 0). For S = 1/2 valence bands, circles with cross (red) and dot (green) indicate the spin orientations pointing into and out of the paper, respectively. For J = 1/2 conduction bands, the labeled orientations correspond to the total angular momenta. The arrows with different thickness represent the asymmetric transition rates at k and −k for right circularly polarized light. (b) and (c) show matrix elements $\frac{1}{2}\mid \langle {\psi }_{\mathrm{c}}(\mathbf{k})\mid {\widehat{p}}_x\pm i{\widehat{p}}_z{\mid {\psi }_{\mathrm{v}}(\mathbf{k})\rangle \mid }^2$ for transitions between highest valence band and lowest conduction band. + and − correspond to right and left circularly polarized light, respectively.