Figure 4

σ ₁(ω) of (a) (Sr_1−x La _x )₂IrO₄ and (b) (Sr_1−x La _x )₃Ir₂O₇ at 10 K. (c) Resonant frequencies of the peaks I (solid squares), α (solid triangles), and β (solid circles). (d) Strengths of the peaks I, α, and β. (e) Normalized spectral weights of the peaks α (red triangles) and β (blue circles) SW(x)/SW(x = 0) of (Sr_1−x La _x )₂IrO₄ (solid symbols) and (Sr_1−x La _x )₃Ir₂O₇ (open symbols).