Fig. 3

Dirac-band excitations in low-disorder AG in a triangular antidot structure. a AG energy band calculation with parameters in Supplementary Table 1 and diagram of Dirac-band transitions for sample I. Transitions in different regimes are illustrated by different colors. b The lowest plot is the joint density of states (JDOS) for the transitions in a. The colored areas show transitions in different regimes. The red trace is the JDOS under Gaussian broadening with width γ = 0.1 meV (this γ is chosen to fit the spectra line shape near E_M). The top yellow trace is the RILS spectrum of Dirac-band excitations in sample I obtained with incident photon energy ħω_i of 1522.88 meV. c RILS spectra of Dirac-band excitations. A non-RILS background has been removed (subtraction details are reported in Supplementary Figures 4–6, and in Supplementary Note 3). ħω_i in meV are indicated. The vertical dashed lines indicate the positions of E_M and E_X. The inset shows a level diagram for E_M and E_X. In the inset, black circles are for holes in c₀₀ band and red circles are for electrons in c₀₁ band. d Top shows a RILS spectrum (purple trace) with ħω_i of 1523.06 meV, and the JDOS (red dashed line, γ = 0.1 meV) that is proportional to scattering intensity due to the single-particle transitions. Bottom: upper traces reveal the spectrum after subtraction of the single-particle JDOS intensities with ħω_i of 1523.06 meV (purple), 1523.01 meV (blue), and 1522.97 meV (green). A schematic plot shows the spin-exciton energy and the gap energy at the M-point. Due to Landau damping, the width of the spin-exciton mode increases