Janus graphene nanoribbons with localized states on a single zigzag edge

• 成果类型: Article
• 署名作者: Song, Shaotang; Teng, Yu; Tang, Weichen; Xu, Zhen; He, Yuanyuan; Ruan, Jiawei; Kojima, Takahiro; Hu, Wenping; Giessibl, Franz J.; Sakaguchi, Hiroshi; Louie, Steven G.; Lu, Jiong
• 署名单位: National University of Singapore; National University of Singapore; Tianjin University; University of California System; University of California Berkeley; United States Department of Energy (DOE); Lawrence Berkeley National Laboratory; Kyoto University; Tianjin University; University of Regensburg
• 刊物名称: Nature
• ISSN/ISSBN: 0028-1107
• DOI: 10.1038/s41586-024-08296-x
• 发表日期: 2025-01-16
• 关键词: on-surface synthesis; spin; metallicity; GROWTH

摘要

Topological design of pi electrons in zigzag-edged graphene nanoribbons (ZGNRs) leads to a wealth of magnetic quantum phenomena and exotic quantum phases1, 2, 3, 4, 5, 6, 7, 8, 9-10. Symmetric ZGNRs typically show antiferromagnetically coupled spin-ordered edge states1,2. Eliminating cross-edge magnetic coupling in ZGNRs not only enables the realization of a class of ferromagnetic quantum spin chains11, enabling the exploration of quantum spin physics and entanglement of multiple qubits in the one-dimensional limit3,12, but also establishes a long-sought-after carbon-based ferromagnetic transport channel, pivotal for ultimate scaling of GNR-based quantum electronics1, 2-3,9,13. Here we report a general approach for designing and fabricating such ferromagnetic GNRs in the form of Janus GNRs (JGNRs) with two distinct edge configurations. Guided by Lieb's theorem and topological classification theory14, 15-16, we devised two JGNRs by asymmetrically introducing a topological defect array of benzene motifs to one zigzag edge, while keeping the opposing zigzag edge unchanged. This breaks the structural symmetry and creates a sublattice imbalance within each unit cell, initiating a spin-symmetry breaking. Three Z-shaped precursors are designed to fabricate one parent ZGNR and two JGNRs with an optimal lattice spacing of the defect array for a complete quench of the magnetic edge states at the 'defective' edge. Characterization by scanning probe microscopy and spectroscopy and first-principles density functional theory confirms the successful fabrication of JGNRs with a ferromagnetic ground-state localized along the pristine zigzag edge.