Magnetism of Topological Boundary States Induced by Boron Substitution in Graphene Nanoribbons

OPEN DATA related to the research publication: Niklas Friedrich, Pedro Brandimarte, Jingcheng Li, Shohei Saito, Shigehiro Yamaguchi, Iago Pozo, Diego Peña, Thomas Frederiksen, Aran Garcia-Lekue, Daniel Sánchez-Portal, and José Ignacio Pascual, <em>Magnetism of Topological Boundary States Induced by Boron Substitution in Graphene Nanoribbons</em>, Phys. Rev. Lett. <strong>125</strong>, 146801 (2020) [arXiv:2004.10280] Abstract: Graphene nanoribbons (GNRs), low-dimensional platforms for carbon-based electronics, show the promising perspective to also incorporate spin polarization in their conjugated electron system. However, magnetism in GNRs is generally associated with localized states around zigzag edges, difficult to fabricate and with high reactivity. Here we demonstrate that magnetism can also be induced away from physical GNR zigzag edges through atomically precise engineering topological defects in its interior. A pair of substitutional boron atoms inserted in the carbon backbone breaks the conjugation of their topological bands and builds two spin-polarized boundary states around them. The spin state was detected in electrical transport measurements through boron-substituted GNRs suspended between the tip and the sample of a scanning tunneling microscope. First-principle simulations find that boron pairs induce a spin 1, which is modified by tuning the spacing between pairs. Our results demonstrate a route to embed spin chains in GNRs, turning them into basic elements of spintronic devices.本公开数据集关联以下研究论文：Niklas Friedrich、Pedro Brandimarte、Jingcheng Li、Shohei Saito、Shigehiro Yamaguchi、Iago Pozo、Diego Peña、Thomas Frederiksen、Aran Garcia-Lekue、Daniel Sánchez-Portal与José Ignacio Pascual合作完成的《Magnetism of Topological Boundary States Induced by Boron Substitution in Graphene Nanoribbons》（《石墨烯纳米带中硼取代诱导的拓扑边界态磁性》），发表于《物理评论快报》(Physical Review Letters) 125卷，146801 (2020) [arXiv:2004.10280]。摘要：石墨烯纳米带（Graphene Nanoribbons, GNRs）作为碳基电子学的低维研究平台，其共轭电子体系具备引入自旋极化特性的可观应用前景。然而，当前石墨烯纳米带的磁性通常仅与锯齿形边缘附近的局域态相关，这类边缘不仅制备难度大，且反应活性较高。本研究证实，通过对石墨烯纳米带内部的拓扑缺陷开展原子级精准工程化修饰，可在远离物理锯齿形边缘的区域诱导产生磁性。插入碳骨架的一对取代硼原子会破坏其拓扑能带的共轭性，并在其周围形成两个自旋极化的边界态。借助悬挂于扫描隧道显微镜（Scanning Tunneling Microscope, STM）针尖与样品之间的硼取代石墨烯纳米带开展电学输运测量，成功探测到该自旋态。第一性原理（First-principle）模拟结果表明，硼原子对可诱导出自旋1态，且可通过调整原子对之间的间距对该自旋态进行调控。本研究成果为在石墨烯纳米带中嵌入自旋链提供了可行路径，使其可作为自旋电子学器件的基本构成单元。