Fig. 2. Anharmonic Mg(1) phonon modes and momentum-resolved measurements from inelastic x-ray scattering.

(A) Phonon DOS of Mg₃Bi₂ from INS at 300 K (blue) and 600 K (red), compared with VACF calculation at 300 K (black) and renormalized DOS from TDEP (gray). The computed total DOS is NW and convolved with the experimental resolution. (B and C) Momentum-resolved IXS measurements on single crystals (markers), compared with DFT phonon dispersions (solid lines) for Mg₃Bi₂ and YbMg₂Bi₂. Blue, green, and red markers correspond to the fitted phonon energy at 80, 300, and 600 K. (D) Brillouin zone (irreducible wedge in red) and high-symmetry points.