Stacking-dependent band gap and quantum transport in trilayer graphene
Stacking-dependent band gap and quantum transport in trilayer graphene
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DOI：
10.1038/nphys2103
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发表时间：
2011-12-01
期刊：
影响因子：
19.6
通讯作者：
Lau, C. N.
中科院分区：
文献类型：
--
作者：
Bao, W.;Jing, L.;Lau, C. N.
石墨烯（1-3）是一种具有手性电荷载体和迷人的电子、机械和热性质的非凡的二维（2D）系统（4，5）。在多层石墨烯（6，7）中，堆叠顺序提供了一个重要但很少探索的自由度，用于调整其电子特性（8）。例如，Bernal堆叠的三层石墨烯（B-TLG）是具有可调带重叠的半金属，并且菱形堆叠的三层石墨烯（r-TLG）被预测为具有可调带隙的半导体（9-17）。由于增强的电子相互作用和竞争对称性，这些多层石墨烯也有望在低电荷密度下表现出丰富的新现象。在这里，我们展示了显着不同的TLG与不同的堆叠顺序，和意想不到的自发能隙开放的电荷中性r-TLG的输运性质。在狄拉克点，B-TLG仍然是金属的，而r-TLG成为绝缘的内在相互作用驱动的差距类似于6毫电子伏。在磁场中，发展良好的量子霍尔（QH）高原r-TLG分裂成三个分支在较高的领域。这种分裂是Lifshitz跃迁的一个标志，这是费米表面的一种拓扑变化，只在r-TLG中发现。我们的研究结果强调了具有不同堆叠顺序的三层石墨烯中丰富的相互作用诱导现象，以及其在电子应用方面的潜力。
Graphene(1-3) is an extraordinary two-dimensional (2D) system with chiral charge carriers and fascinating electronic, mechanical and thermal properties(4,5). In multilayer graphene(6,7), stacking order provides an important yet rarely explored degree of freedom for tuning its electronic properties(8). For instance, Bernal-stacked trilayer graphene (B-TLG) is semi-metallic with a tunable band overlap, and rhombohedral-stacked trilayer graphene (r-TLG) is predicted to be semiconducting with a tunable band gap(9-17). These multilayer graphenes are also expected to exhibit rich novel phenomena at low charge densities owing to enhanced electronic interactions and competing symmetries. Here we demonstrate the dramatically different transport properties in TLG with different stacking orders, and the unexpected spontaneous gap opening in charge neutral r-TLG. At the Dirac point, B-TLG remains metallic, whereas r-TLG becomes insulating with an intrinsic interaction-driven gap similar to 6 meV. In magnetic fields, well-developed quantum Hall (QH) plateaux in r-TLG split into three branches at higher fields. Such splitting is a signature of the Lifshitz transition, a topological change in the Fermi surface, that is found only in r-TLG. Our results underscore the rich interaction-induced phenomena in trilayer graphene with different stacking orders, and its potential towards electronic applications.