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arXiv 2407.04532cond-mat.mes-hallcond-mat.mtrl-sci
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滑动双层石墨烯的自由能势垒与热-量子行为

Free energy barrier and thermal-quantum behavior of sliding bilayer graphene

Fondazione Istituto Italiano di Tecnologia(意大利理工学院);Université de Liège(列日大学)

Jean Paul Nery, Lorenzo Monacelli, Francesco Mauri

AI总结:

本文利用自洽谐振近似计算双层石墨烯滑动过程中的自由能势垒,发现100 K以上热振动使势垒降低超过30%,显著改善了理论与实验的一致性,为宏观系统自由能势垒的热效应研究提供了通用方法。

摘要:

在多层石墨烯中,层间的堆叠顺序对电子性质以及超导电性的表现起着至关重要的作用。通过施加剪切应力,可以诱导不同层之间发生滑动,从而改变堆叠顺序。本文以双层石墨烯为研究对象,分析了离子涨落如何改变不同堆叠平衡态之间的自由能势垒。我们采用最先进的自洽谐振近似方法计算自由能势垒,该方法可以在不稳定构型下进行评估。我们发现,在100 K以上,由于热振动,势垒大幅降低了30%以上,这显著改善了先前第一性原理理论工作与单晶石墨实验之间的一致性。随着温度升高,势垒在约500 K之前几乎保持不变,只有在更高温度下才出现更明显的下降。我们的方法具有普适性,为在其他宏观系统中系统性地考虑自由能势垒中的热效应铺平了道路。

英文摘要:

In multilayer graphene, the stacking order of the layers plays a crucial role in the electronic properties and the manifestation of superconductivity. By applying shear stress, it is possible to induce sliding between different layers, altering the stacking order. Here, focusing on bilayer graphene, we analyze how ionic fluctuations alter the free energy barrier between different stacking equilibria. We calculate the free energy barrier through the state-of-the-art self-consistent harmonic approximation, which can be evaluated at unstable configurations. We find that above 100 K there is a large reduction of the barrier of more than 30% due to thermal vibrations, which significantly improves the agreement between previous first-principles theoretical work and experiments in a single graphite crystal. As the temperature increases, the barrier remains nearly constant up to around 500 K, with a more pronounced decrease only at higher temperatures. Our approach is general and paves the way for systematically accounting for thermal effects in free energy barriers of other macroscopic systems.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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