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Abnormally Strong Electron–Phonon Scattering Induced Unprecedented Reduction in Lattice Thermal Conductivity of Two-Dimensional Nb₂C

Huang, Yongda, Zhou, Jian, Wang, Guanjie, Sun, Zhimei
Journal of the American Chemical Society 2019 v.141 no.21 pp. 8503-8508
energy, thermal conductivity
In most materials the electron–phonon (e-p) scattering is far weaker than phonon–phonon (p-p) scattering, and the e-p scattering is usually proportional to the e-p coupling strength. Here, we report strong e-p scattering but low e-p coupling strength in two-dimensional(2D) Nb₂C by first-principles calculations. Moreover, the intensity of e-p scattering is close to that of p-p scattering at 300 K in sharp contrast to normal cases. This abnormal e-p scattering is understood by a specific feature that the energy difference between occupied and empty electron states near the Fermi level is in the order of the characteristic phonon energy. By calculating the phonon transport property of 2D Nb₂C, we show that this strong e-p scattering can result in great reduction in the lattice thermal conductivity.Our work also highlights a new way for searching novel 2D materials with low lattice thermal conductivity.