2D beryllium polynitrides or beryllonitrene is a newly synthesized layered material displaying anisotropic Dirac cones and van Hove singularity (VHS) located only ≈0.5 eV above the Fermi level. Using the Boltzmann transport equation with many-body effects and first-principles calculations, it is uncovered that beryllonitrene has an in-plane anisotropic room-temperature phonon thermal conductivity (κph) of 78.6 and 98.8 W mK−1, and an electron thermal conductivity (κe) of 23.0 and 60.7 W mK−1, along the in-plane directions. κph is dominated by the large heat capacity flexural acoustic (ZA) modes, which are susceptible to three-phonon and four-phonon scatterings but rather immune to scattering onto electrons. Filling the Dirac cones till VHS and above gradually enhances the phonon–electron coupling and monotonically decreases κph by up to 55%. Instead, κe displays unusual nonmonotonic variations with the increase in the carrier density and follows the electron density of states at corresponding Fermi levels. The results shed light on the thermal and electrical transport properties in beryllonitrene and reveal a thermal conductivity modulation mechanism that includes a 60% increase of κe upon filling of the Dirac cones until VHS.
Bibliographical noteFunding Information:
The authors would like to thank Dr. Shouhang Li for valuable discussions. T.F. acknowledges support from DFG FR‐2833/7 and National Natural Science Foundation of China (Grant No. U1930402). Z.T. acknowledges the support by National Natural Science Foundation (Grant No. 52106068), China Postdoctoral Science Foundation (Grant No. 2020M680127), Guangdong Basic and Applied Basic Research Foundation (Grants Nos. 2020A1515110838 and 2021A1515011688), and Shenzhen Science and Technology Program (Grant No. RCBS20200714114919142). Simulations were preformed at the Tianhe2‐JK of Beijing Computational Science Research Center.
© 2022 The Authors. Advanced Functional Materials published by Wiley-VCH GmbH
- 2D materials
- density functional theory
- thermal conductivity