Janus graphene nanoribbons with a single ferromagnetic zigzag edge

• URL: http://arxiv.org/abs/2406.05608v2
• Date: Sun, 20 Oct 2024 03:34:37 GMT
• Title: Janus graphene nanoribbons with a single ferromagnetic zigzag edge
• Authors: Shaotang Song, Yu Teng, Weichen Tang, Zhen Xu, Yuanyuan He, Jiawei Ruan, Takahiro Kojima, Wenping Hu, Franz J Giessibl, Hiroshi Sakaguchi, Steven G Louie, Jiong Lu,
• Abstract summary: Topological design of pi-electrons in zigzag-edged graphene nanoribbons (ZGNRs) leads to magnetic quantum phenomena and exotic quantum phases. Eliminating cross-edge magnetic coupling in ZGNRs enables the realization of a new class of ferromagnetic quantum spin chains. Here, we report a general approach for designing and fabricating such ferromagnetic GNRs in the form of Janus GNRs with two distinct edge configurations.
• Score: 5.160365538756164
• License: http://creativecommons.org/licenses/by/4.0/
• Abstract: Topological design of pi-electrons in zigzag-edged graphene nanoribbons (ZGNRs) leads to a wealth of magnetic quantum phenomena and exotic quantum phases. Symmetric ZGNRs typically exhibit antiferromagnetically coupled spin-ordered edge states. Eliminating cross-edge magnetic coupling in ZGNRs not only enables the realization of a new class of ferromagnetic quantum spin chains, enabling the exploration of quantum spin physics and entanglement of multiple qubits in the 1D limit, but also establishes a long-sought carbon-based ferromagnetic transport channel, pivotal for ultimate scaling of GNR-based quantum electronics. However, designing such GNRs entails overcoming daunting challenges, including simultaneous breaking of structural and spin symmetries, and designing elegant precursors for asymmetric fabrication of reactive zigzag edges. Here, we report a general approach for designing and fabricating such ferromagnetic GNRs in the form of Janus GNRs with two distinct edge configurations. Guided by Lieb's theorem and topological classification theory, we devised two JGNRs by asymmetrically introduced a topological defect array of benzene motifs to one zigzag edge, while keeping the opposing zigzag edge unchanged. This breaks structural symmetry and creates a sublattice imbalance within each unit cell, initiating a spin symmetry breaking. Three Z-shape 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 via scanning probe microscopy/spectroscopy and first-principles density functional theory confirms the successful fabrication of Janus GNRs with ferromagnetic ground state delocalised along the pristine zigzag edge.

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