Phonon linewidths in twisted bilayer graphene near the magic angle

S Mandal and I Maity and HR Krishnamurthy and M Jain, PHYSICAL REVIEW B, 110, 125421 (2024).

DOI: 10.1103/PhysRevB.110.125421

We present a computational study of the phonon linewidths in twisted bilayer graphene arising from electronphonon and phonon-phonon interactions. The electronic structure is calculated using distance- dependent transfer integrals based on the atomistic Slater-Koster tight- binding formalism including electron-electron interactions treated at the Hartree level, and the phonons are calculated using classical force fields. These ingredients are used to calculate the phonon linewidths arising from electron-phonon interactions. Furthermore, effects of the phononphonon interactions on the linewidths are computed using the mode- projected velocity autocorrelation function obtained from classical molecular dynamics. We predict a moire potential induced splitting of the Raman-active G mode, near the magic angle, which arises due to contributions from high-symmetry stacking regions. Our findings show that both electron-phonon and anharmonic effects have a significant impact on the linewidth of this mode near the magic angle.

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