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Electron-phonon coupling in half-Heusler compounds: A comparative study of TiCoSb and TiNiSn

发布时间：2025-03-08点击次数：

  • DOI码：10.1103/PhysRevB.111.115201
  • 发表刊物：Physical Review B
  • 刊物所在地：美国
  • 项目来源：National Natural Science Foundation of China (Grants No. 12374079, No. 12174017, and No. 11774416).
  • 摘要：Electron-phonon coupling has inspired broad research because of the dominant role in electron and phonon transport properties, whereas how to control the coupling strength through band-structure engineering is a widely debated issue in solid-state physics. Here, we establish a general relationship between valence-band shape and electron-phonon coupling by conducting a comparative study of typical half-Heusler compounds TiCoSb and TiNiSn. The competition between symmetry-allowed 𝑑−𝑑 and 𝑝−𝑑 orbital couplings eventually determines the valence-band-edge shape. The 𝑑−𝑑 coupling between Co/Ni and Ti atoms favors a unique wavelike valence band with multiple nearly equal-energy valleys in TiCoSb and the 𝑝−𝑑 coupling between Sb/Sn and Ti atoms prefers a single parabolic valence band in TiNiSn. More importantly, the wavelike band effectively strengthens the electron-phonon coupling by introducing the intervalley scattering that remains stronger than the intravalley scattering. In contrast, the single parabolic band seriously suppresses the scattering process because the intravalley scattering dominates the electron-phonon coupling. The different scattering mechanism results in a series of anomalous electron and phonon transport properties, for example, in sharp contrast to TiNiSn, TiCoSb has a more pronounced decrease in band gap with temperature and a weaker temperature dependence of lattice thermal conductivity. Our findings provide universal insights into the effects of complex band structure on electron-phonon coupling and help to develop different strategies to improve and design better thermoelectric materials.
  • 备注：周冉, 梁汉普, 时洪亮*, 段益峰*
  • 论文类型：期刊论文
  • 学科门类：理学
  • 一级学科：物理学
  • 文献类型：J
  • 卷号：111
  • 期号：11
  • 页面范围：115201
  • 是否译文：否
  • 发表时间：2025-03-07
  • 收录刊物：SCI
  • 发布期刊链接：https://journals.aps.org/prb/abstract/10.1103/PhysRevB.111.115201

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下一条：Temperature-renormalized phonon and electron transport in thermoelectric Mg3Sb2: Dominant role of anharmonic phonon modes

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段益峰

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