金属ε-氮化钽（ε-TaN）中电子与声子的平衡热输运
Balanced electron and phonon heat transport in metallic $\varepsilon$-TaN
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中文总结 AI 辅助
本研究预测并实现了兼具高电子与晶格热导率的金属ε-TaN，其热导率平衡源于电子与晶格的特定性质，计算与实验结果吻合。
中文摘要 AI 辅助
大多数高导热材料属于两类之一：金属中热量主要由电子携带，绝缘体中热输运则以声子贡献为主。兼具高电子热导率和晶格热导率的材料十分罕见，因为利于电子输运的机制通常会抑制声子输运，反之亦然。本文报道了这类材料——金属ε-TaN的理论预测与实验实现。我们的计算预测，室温下单晶体的总热导率为273±5Wm⁻¹K⁻¹，晶粒尺寸0.5μm的多晶体为145±5Wm⁻¹K⁻¹，该金属的晶格贡献占比达79%，异常地高；后者与我们对多晶样品进行的局部瞬态热反射测量得到的~130Wm⁻¹K⁻¹结果一致。我们表明，ε-TaN的电子与晶格热导率平衡源于电子侧的大费米速度与小费米态密度，以及晶格侧的大声速与宽声子带隙的结合。
英文摘要
Most materials with high thermal conductivity belong to one of two classes: metals, where heat is carried predominantly by electrons, and insulators, where heat transport is dominated by the phonon contribution. Materials that combine substantial electronic thermal conductivity and lattice thermal conductivity are rare, because the mechanisms that favor electron transport typically suppress phonon transport, and vice versa. Here, we report the theoretical prediction and experimental realization of such a material, metallic $\varepsilon$-TaN. Our calculations predict a total thermal conductivity at room-temperature of 273$\pm$5Wm$^{-1}$K$^{-1}$ in single crystals and 145$\pm$5Wm$^{-1}$K$^{-1}$ in polycrystals with 0.5$μ$m grains, with an unusually large lattice contribution (79%) for a metal. The latter value is in agreement with our local transient thermoreflectance measurements on polycrystalline samples yielding $\sim$130Wm$^{-1}$K$^{-1}$. We show that the balanced electronic and lattice thermal conductivities of $\varepsilon$-TaN originate from a combination of large Fermi velocity and small Fermi density of states on the electron side, and large speed of sound and wide phonon gap on the lattice side.
