Electrically Induced Dirac Fermions in Graphene Nanoribbons
Electrically Induced Dirac Fermions in Graphene Nanoribbons
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DOI：
10.1021/acs.nanolett.1c03596
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发表时间：
2021-10-29
期刊：
影响因子：
10.8
通讯作者：
Kaxiras，Efthimios
中科院分区：
文献类型：
--
作者：
Pizzochero，Michele;Tepliakov，Nikita;Kaxiras，Efthimios
石墨烯纳米带被广泛认为是下一代碳基器件的有前途的构建块。其应用前景的一个关键问题是其电子结构是否可以外部控制。在这里，我们结合联合收割机简单的模型哈密顿量与广泛的第一性原理计算研究扶手椅型石墨烯纳米带的横向电场的响应。这样的场可以通过横向选通纳米取向物或沿边缘沿着掺入双极化学共掺杂剂来实现。我们发现，该领域诱导的半金属相变的半金属相具有零能量狄拉克费米子传播沿着扶手椅边缘。该转变发生在临界场，该临界场与纳米带的宽度成反比。这些发现是普遍的IV组蜂窝晶格，包括硅烯和锗烯纳米带，无论边缘终止的类型。总的来说，我们的研究结果创造了新的机会，以电气工程狄拉克半金属相，否则半导体石墨烯类纳米带。
Graphene nanoribbons are widely regarded as promising building blocks for next-generation carbon-based devices. A critical issue to their prospective applications is whether their electronic structure can be externally controlled. Here, we combine simple model Hamiltonians with extensive first-principles calculations to investigate the response of armchair graphene nanoribbons to transverse electric fields. Such fields can be achieved either upon laterally gating the nanoribbon or incorporating ambipolar chemical codopants along the edges. We reveal that the field induces a semiconductor-to-semimetal transition with the semimetallic phase featuring zero-energy Dirac fermions that propagate along the armchair edges. The transition occurs at critical fields that scale inversely with the width of the nanoribbons. These findings are universal to group-IV honeycomb lattices, including silicene and germanene nanoribbons, irrespective of the type of edge termination. Overall, our results create new opportunities to electrically engineer Dirac semimetallic phases in otherwise semiconducting graphene-like nanoribbons.