Bernal-stacked tetralayer graphene (4LG) exhibits intriguing low-energy properties, featuring two massive sub-bands and showcasing diverse features of topologically distinct, anisotropic Fermi surfaces, including Lifshitz transitions and trigonal warping. Here, we study the influence of the band structure on electron dynamics within 4LG using transverse magnetic focusing. Our analysis reveals two distinct focusing peaks corresponding to the two sub-bands. Furthermore, we uncover a pronounced dependence of the focusing spectra on crystal orientations, indicative of an anisotropic Fermi surface. Utilizing the semiclassical model, we attribute this orientation-dependent behavior to the trigonal warping of the band structure. This phenomenon leads to variations in electron trajectories based on crystal orientation. Our findings not only enhance our understanding of the dynamics of electrons in 4LG but also offer a promising method for probing anisotropic Fermi surfaces in other materials.

中文翻译：

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通过横向磁聚焦探测四层石墨烯中的各向异性费米面


伯纳尔堆叠四层石墨烯 (4LG) 表现出有趣的低能特性，具有两个巨大的子带，并展示了拓扑独特的各向异性费米表面的多种特征，包括利夫希兹跃迁和三角翘曲。在这里，我们使用横向磁聚焦研究了 4LG 内能带结构对电子动力学的影响。我们的分析揭示了对应于两个子带的两个不同的聚焦峰。此外，我们发现聚焦光谱对晶体取向的明显依赖性，表明费米面具有各向异性。利用半经典模型，我们将这种方向相关的行为归因于能带结构的三角扭曲。这种现象导致基于晶体取向的电子轨迹发生变化。我们的发现不仅增强了我们对 4LG 中电子动力学的理解，而且还为探测其他材料中的各向异性费米表面提供了一种有前途的方法。