Pizzochero Michele, Barin Gabriela Borin, Čerņevičs Kristia Ns, Wang Shiyong, Ruffieux Pascal, Fasel Roman, Yazyev Oleg V
Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, United States.
J Phys Chem Lett. 2021 May 20;12(19):4692-4696. doi: 10.1021/acs.jpclett.1c00921. Epub 2021 May 12.
We unveil the nature of the structural disorder in bottom-up zigzag graphene nanoribbons along with its effect on the magnetism and electronic transport on the basis of scanning probe microscopies and first-principles calculations. We find that edge-missing -xylene units emerging during the cyclodehydrogenation step of the on-surface synthesis are the most common point defects. These "bite" defects act as spin-1 paramagnetic centers, severely disrupt the conductance spectrum around the band extrema, and give rise to spin-polarized charge transport. We further show that the electronic conductance across graphene nanoribbons is more sensitive to "bite" defects forming at the zigzag edges than at the armchair ones. Our work establishes a comprehensive understanding of the low-energy electronic properties of disordered bottom-up graphene nanoribbons.
基于扫描探针显微镜和第一性原理计算，我们揭示了自下而上的锯齿形石墨烯纳米带中结构无序的本质及其对磁性和电子输运的影响。我们发现，在表面合成的环脱氢步骤中出现的边缘缺失的二甲苯单元是最常见的点缺陷。这些“咬痕”缺陷作为自旋-1顺磁中心，严重扰乱了能带极值附近的电导谱，并导致自旋极化电荷输运。我们进一步表明，穿过石墨烯纳米带的电子电导对在锯齿形边缘形成的“咬痕”缺陷比在扶手椅形边缘形成的缺陷更敏感。我们的工作建立了对无序的自下而上的石墨烯纳米带的低能电子性质的全面理解。
