Extremely Large Response of Phonon Coherence in Twisted Penta‐NiN2 Bilayer

Abstract

AbstractTwisting has recently been demonstrated as an effective strategy for tuning the interactions between particles or quasi‐particles in layered materials. Motivated by the recent experimental synthesis of pentagonal NiN2 sheet [ACS Nano 2021, 15, 13539], for the first time, the response of phonon coherence to twisting in bilayer penta‐NiN2, going beyond the particle‐like phonon transport is studied. By using the unified theory of phonon transport and high order lattice anharmonicity, together with the self‐consistent phonon theory, it is found that the lattice thermal conductivity is reduced by 80.6% from 33.35 to 6.47 W m−1 K−1 at 300 K when the layers are twisted. In particular, the contribution of phonon coherence is increased sharply by an order of magnitude, from 0.21 to 2.40 W m−1 K−1 , due to the reduced differences between the phonon frequencies and enhanced anharmonicity after the introduction of twist. The work provides a fundamental understanding of the phonon interaction in twisted pentagonal sheets.