TY - JOUR
T1 - Degradation of Phonons in Disordered Moiré Superlattices
AU - Ochoa, Héctor
AU - Fernandes, Rafael M.
N1 - Publisher Copyright:
© 2022 American Physical Society.
PY - 2022/2/11
Y1 - 2022/2/11
N2 - The elastic collective modes of a moiré superlattice arise not from vibrations of a rigid crystal but from the relative displacement between the constituent layers. Despite their similarity to acoustic phonons, these modes, called phasons, are not protected by any conservation law. Here, we show that disorder in the relative orientation between the layers and thermal fluctuations associated with their sliding motion degrade the propagation of sound in the moiré superlattice. Specifically, the phason modes become overdamped at low energies and acquire a finite gap, which displays a universal dependence on the twist-angle variance. Thus, twist-angle inhomogeneity is manifested not only in the noninteracting electronic structure of moiré systems, but also in their phononlike modes. More broadly, our results have important implications for the electronic properties of twisted moiré systems that are sensitive to the electron-phonon coupling.
AB - The elastic collective modes of a moiré superlattice arise not from vibrations of a rigid crystal but from the relative displacement between the constituent layers. Despite their similarity to acoustic phonons, these modes, called phasons, are not protected by any conservation law. Here, we show that disorder in the relative orientation between the layers and thermal fluctuations associated with their sliding motion degrade the propagation of sound in the moiré superlattice. Specifically, the phason modes become overdamped at low energies and acquire a finite gap, which displays a universal dependence on the twist-angle variance. Thus, twist-angle inhomogeneity is manifested not only in the noninteracting electronic structure of moiré systems, but also in their phononlike modes. More broadly, our results have important implications for the electronic properties of twisted moiré systems that are sensitive to the electron-phonon coupling.
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U2 - 10.1103/PhysRevLett.128.065901
DO - 10.1103/PhysRevLett.128.065901
M3 - Article
C2 - 35213205
AN - SCOPUS:85124984636
SN - 0031-9007
VL - 128
JO - Physical review letters
JF - Physical review letters
IS - 6
M1 - 065901
ER -