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Fig. 1 Comparison of calculated temperature-dependent carrier mobilities.
對此,復旦大學未來資訊創新學院張浩副教授團隊和北京理工大學物理學院的周金建教授團隊合作,基於第一性原理計算,系統揭示了長程四極矩效應對新興的二維材料家族—-MA₂X₄(如MoSi₂N₄和WSi₂N₄)的電和熱輸運效能的關鍵影響。他們發現,在考慮四極子效應後,室溫下MoSi₂N₄中電子與空穴的遷移率分別下降了25.4%和12.8%,WSi₂N₄中則高達19.2%和52.3%,這意味著以往僅考慮偶極矩項和短程相互作用的模型可能高估了材料遷移率效能。在熱輸運方面,長程電聲耦合亦不可忽視,其導致三聲子限制的晶格熱導率分別下降了3.6%(MoSi₂N₄)和2.4%(WSi₂N₄)。

更進一步,研究團隊還提出並推導了三聲子散射通道的選擇規則,揭示aoo/ooo(其中a與o分別指代聲學與光學模)散射通道在這兩種材料中占主導地位,為深入理解二維材料的熱輸運機制提供了理論依據。該文近期發表於 npj Computational Materials 11:166(2025),英文標題與摘要如下,點選左下角“閱讀原文”可以自由獲取論文PDF。
Enhanced long-range quadrupole effects in 2D MSi2N4: impacts on electric and thermal transport
Juan Zhang, Jiayi Gong, Hongyu Chen, Lei Peng, Hezhu Shao, Yan Cen, Jun Zhuang, Heyuan Zhu, Jinjian Zhou & Hao Zhang
Long-range higher-order multipolar electron–phonon (e-ph) interactions beyond the dipole-like Fröhlich interactions have long been neglected in the description of various physical properties. Here we demonstrate the contribution from quadrupole effect to the electric and thermal transport properties of monolayer MSi2N4 (M = Mo/W) systems. The quadrupole effect reduces the electron and hole mobilities at 300 K by 25.4%, 12.8% for MoSi2N4, and by 19.2%, 52.3% for WSi2N4, respectively. For n- and p-type monolayers with modest dopings by fixing the carrier concentration to 1.0 × 1014 cm−2, the dipole-like e-ph interaction decreases the three-phonon-limited lattice thermal conductivities κl by 17.9% and 43.5% for monolayer MoSi2N4 and WSi2N4, respectively. However, further considerations of quadrupole e-ph interaction shrink such reductions of three-phonon-limited κl to only 3.6% and 2.4%, respectively due to the cancellation effects. Our results highlight the potential of MSi2N4 monolayers as promising candidates for advanced micro-electronic applications.

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