Zhao Chenxiao, Huang Qiang, Valenta Leoš, Eimre Kristjan, Yang Lin, Yakutovich Aliaksandr V, Xu Wangwei, Ma Ji, Feng Xinliang, Juríček Michal, Fasel Roman, Ruffieux Pascal, Pignedoli Carlo A
Empa-Swiss Federal Laboratories for Materials Science and Technology, Dübendorf 8600, Switzerland.
Faculty of Chemistry and Food Chemistry, and Center for Advancing Electronics Dresden, Technical University of Dresden, Dresden 01062, Germany.
Phys Rev Lett. 2024 Jan 26;132(4):046201. doi: 10.1103/PhysRevLett.132.046201.
Atomically precise graphene nanoflakes called nanographenes have emerged as a promising platform to realize carbon magnetism. Their ground state spin configuration can be anticipated by Ovchinnikov-Lieb rules based on the mismatch of π electrons from two sublattices. While rational geometrical design achieves specific spin configurations, further direct control over the π electrons offers a desirable extension for efficient spin manipulations and potential quantum device operations. To this end, we apply a site-specific dehydrogenation using a scanning tunneling microscope tip to nanographenes deposited on a Au(111) substrate, which shows the capability of precisely tailoring the underlying π-electron system and therefore efficiently manipulating their magnetism. Through first-principles calculations and tight-binding mean-field-Hubbard modeling, we demonstrate that the dehydrogenation-induced Au-C bond formation along with the resulting hybridization between frontier π orbitals and Au substrate states effectively eliminate the unpaired π electron. Our results establish an efficient technique for controlling the magnetism of nanographenes.
被称为纳米石墨烯的原子精确石墨烯纳米片已成为实现碳磁性的一个有前景的平台。基于来自两个子晶格的π电子的不匹配，其基态自旋构型可以通过奥夫钦尼科夫 - 利布规则来预测。虽然合理的几何设计可以实现特定的自旋构型，但对π电子的进一步直接控制为有效的自旋操纵和潜在的量子器件操作提供了理想的扩展。为此，我们使用扫描隧道显微镜尖端对沉积在Au(111)衬底上的纳米石墨烯进行位点特异性脱氢，这显示了精确剪裁底层π电子系统并因此有效操纵其磁性的能力。通过第一性原理计算和紧束缚平均场 - 哈伯德模型，我们证明脱氢诱导的Au - C键形成以及由此产生的前沿π轨道与Au衬底态之间的杂化有效地消除了未配对的π电子。我们的结果建立了一种控制纳米石墨烯磁性的有效技术。
