新加坡国立大学Lu, Jiong团队报了同时存在强相关性和拓扑不稳定性的高度纠缠的多自由基纳米石墨烯。相关研究成果于2024年2月19日发表在《自然—化学》。

开壳纳米石墨烯表现出由拓扑不稳定性或强电子-电子相互作用引起的非常规π磁性。然而，传统的设计方法通常局限于单个磁原点，这可能会限制开壳纳米石墨烯中相关自旋的数量或磁有序的类型。

该文中，研究人员提出了一种结合了拓扑不稳定性和电子-电子相互作用的设计策略，在Au（111）上制备了一个大的完全融合的“蝴蝶”形四自由基纳米石墨烯。研究人员分别使用键分辨扫描隧道显微镜和自旋激发光谱，来分辨分子骨架并揭示强相关的开壳特征。

这种纳米石墨烯包含四个具有铁磁和反铁磁相互作用的不成对电子，具有多体单线态基态和强多自旋纠缠，这在多体计算中得到了很好的描述。此外，研究人员使用镍烯磁性探针研究了纳米石墨烯的磁性和自旋态。在多自由基纳米石墨烯中压印和表征多体强相关自旋的能力，为量子信息技术的未来进步铺平了道路。

附：英文原文

Title: Highly entangled polyradical nanographene with coexisting strong correlation and topological frustration

Author: Song, Shaotang, Pinar Sol, Andrs, Matj, Adam, Li, Guangwu, Stetsovych, Oleksandr, Soler, Diego, Yang, Huimin, Telychko, Mykola, Li, Jing, Kumar, Manish, Chen, Qifan, Edalatmanesh, Shayan, Brabec, Jiri, Veis, Libor, Wu, Jishan, Jelinek, Pavel, Lu, Jiong

Issue&Volume: 2024-02-19

Abstract: Open-shell nanographenes exhibit unconventional π-magnetism arising from topological frustration or strong electron–electron interaction. However, conventional design approaches are typically limited to a single magnetic origin, which can restrict the number of correlated spins or the type of magnetic ordering in open-shell nanographenes. Here we present a design strategy that combines topological frustration and electron–electron interactions to fabricate a large fully fused ‘butterfly’-shaped tetraradical nanographene on Au(111). We employ bond-resolved scanning tunnelling microscopy and spin-excitation spectroscopy to resolve the molecular backbone and reveal the strongly correlated open-shell character, respectively. This nanographene contains four unpaired electrons with both ferromagnetic and anti-ferromagnetic interactions, harbouring a many-body singlet ground state and strong multi-spin entanglement, which is well described by many-body calculations. Furthermore, we study the magnetic properties and spin states in the nanographene using a nickelocene magnetic probe. The ability to imprint and characterize many-body strongly correlated spins in polyradical nanographenes paves the way for future advancements in quantum information technologies.

DOI: 10.1038/s41557-024-01453-9

Source: https://www.nature.com/articles/s41557-024-01453-9