Ultraheavy and Ultrarelativistic Dirac Quasiparticles in Sandwiched Graphenes
Ultraheavy and Ultrarelativistic Dirac Quasiparticles in Sandwiched Graphenes
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DOI：
10.1021/acs.nanolett.9b04979
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发表时间：
2020-05-13
期刊：
影响因子：
10.8
通讯作者：
Kruchkov, Alexander
中科院分区：
文献类型：
--
作者：
Carr, Stephen;Li, Chenyuan;Kruchkov, Alexander
在量子材料中表现出无色散(平坦)带共存、穿透色散(陡峭)带的电子会产生强关联现象，并与非常规超导电性有关。我们发现，在扭曲的夹层石墨烯(TSWG)中，如果扭曲1.5度，陡峭的狄拉克锥体可以在相同的能量尺度下与戏剧性的能带平坦共存。这种现象在简化的连续介质模型中是不稳定的。这封信的主要结果是，平带变得稳定只是我们原子计算中包含的晶格驰豫过程的结果。此外，外场可以改变狄拉克锥顶和平带之间的相对能量偏移量，增强带杂化，从而可以控制相关相位。我们的工作建立了扭曲夹层石墨烯作为研究强相互作用二维量子物质的新平台。
Electrons in quantum materials exhibiting coexistence of dispersion-less (flat) bands piercing dispersive (steep) bands give rise to strongly correlated phenomena and are associated with unconventional superconductivity. We show that in twisted sandwiched graphene (TSWG)-a three-layer van der Waals heterostructure with a twisted middle layer-steep Dirac cones can coexist with dramatic band flattening at the same energy scale, if twisted by 1.5 degrees. This phenomenon is not stable in the simplified continuum models. The key result of this Letter is that the flat bands become stable only as a consequence of lattice relaxation processes included in our atomistic calculations. Further on, external fields can change the relative energy offset between the Dirac cone vertex and the flat bands and enhance band hybridization, which could permit controlling correlated phases. Our work establishes twisted sandwiched graphene as a new platform for research into strongly interacting two-dimensional quantum matter.