Determination of the trigonal warping orientation in Bernal-stacked bilayer graphene via scanning tunneling microscopy
Determination of the trigonal warping orientation in Bernal-stacked bilayer graphene via scanning tunneling microscopy
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DOI：
10.1103/physrevb.101.161103
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发表时间：
2020-04-06
影响因子：
3.7
通讯作者：
Velasco, Jairo, Jr.
中科院分区：
文献类型：
--
作者：
Joucken, Frederic;Ge, Zhehao;Velasco, Jairo, Jr.
在多层(N>；=2)石墨烯薄膜和石墨中，低能电子态在K点附近存在强烈的三角翘曲。它对Lifshitz转变和各向异性弹道传输等现象负责。然而，三角翘曲相对于布里渊区中心的绝对取向并未达成一致。在这里，我们使用准粒子散射实验的门控双层石墨烯/六方氮化硼异质结来解决这个分歧。我们比较了在远离电荷中性点的不同能量下获得的散射干涉图的傅里叶变换与基于紧束缚的联结态密度模拟。这种比较使得能够明确地确定双层石墨烯低能态的三角翘曲方向。我们的实验技术有望准直接地研究门控二维材料能带结构的精细特征，如拓扑跃迁、层间杂化和莫尔微带。
The existence of strong trigonal warping around the K point for the low-energy electronic states in multilayer (N >= 2) graphene films and graphite is well established. It is responsible for phenomena such as Lifshitz transitions and anisotropic ballistic transport. The absolute orientation of the trigonal warping with respect to the center of the Brillouin zone is, however, not agreed upon. Here, we use quasiparticle scattering experiments on a gated bilayer graphene/hexagonal boron nitride heterostructure to settle this disagreement. We compare Fourier transforms of scattering interference maps acquired at various energies away from the charge neutrality point with tight-binding-based joint density of states simulations. This comparison enables unambiguous determination of the trigonal warping orientation for bilayer graphene low-energy states. Our experimental technique is promising for quasidirectly studying fine features of the band structure of gated two-dimensional materials such as topological transitions, interlayer hybridization, and moire minibands.