三层石墨烯中光电子强度的能带选择性模拟与收敛贝里相位
Band-selective simulation of photoelectron intensity and converging Berry phase in trilayer graphene
AI总结：
本研究通过紧束缚框架下的能带选择性模拟，发现ABA堆叠三层石墨烯的贝里相位随结合能变化并在带接触点收敛，为调控贝里相位及相关新奇量子现象提供了新方法。
摘要：
贝里相位是理解量子力学现象（如阿哈罗诺夫-玻姆效应与石墨烯中的反常霍尔效应）的核心要素之一。单层和双层石墨烯中的贝里相位，已通过动量空间中闭合回路上光电子强度的各向异性分布，以及其随光偏振旋转产生的特征角度偏转得到证实。\n本文在紧束缚近似框架下，开展了三层石墨烯光电子强度的能带选择性模拟，以探究其贝里相位特性。ABC堆叠与ABA堆叠的三层石墨烯均表现出特征性的光电子强度分布旋转角，与二者已知的贝里相位预测结果一致。\n但令人意外的是，在ABA堆叠的三层石墨烯中，当趋近导带与价带的带接触点时，旋转角会发生变化，表明贝里相位随结合能的变化而改变。这种结合能依赖的贝里相位，源于ABA堆叠三层石墨烯中在带接触点处收敛的两条电子能带的杂化增强，最终形成收敛贝里相位。这些发现将为调控贝里相位及由此衍生的新奇量子现象提供有效途径。
英文摘要：
Berry phase is one of the key elements to understand quantum-mechanical phenomena such as the Aharonov-Bohm effect and the unconventional Hall effect in graphene. The Berry phase in monolayer and bilayer graphene has been manifested by the anisotropic distribution of photoelectron intensity along a closed loop in the momentum space as well as its rotation by a characteristic angle upon rotating light polarization. Here we report the band-selective simulation of photoelectron intensity of trilayer graphene to understand its Berry phase within the tight-binding formalism. ABC- and ABA-stacked trilayer graphene show characteristic rotational angles of photoelectron intensity distribution, as predicted from their well-known Berry phases. Surprisingly, however, in ABA-stacked trilayer graphene, the rotational angle changes upon approaching toward the band touching point between the conduction and valence bands, which suggest that Berry phase changes as a function of binding energy. The binding energy-dependent Berry phase is attributed to the enhanced hybridization of the two electron bands of ABA-stacked trilayer graphene that converge at the band touching point, resulting in the converging Berry phase. These findings will provide an efficient way of tuning Berry phase and hence exotic phenomena stemming from the Berry phase.
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