上海科技大学研究小组报道了表面合成自旋冕体的集体磁性。这一研究成果发表在2025年3月18日出版的国际学术期刊《美国化学会杂志》上。

在这里，课题组提出了一个开壳的六个自由基的冠状体通过表面合成。该自旋冕状体显示了由六个未配对π电子沿共轭路径的最近邻交换相互作用和次近邻交换相互作用产生的集体自旋态。用非弹性电子隧道能谱法对从基态到激发态的自旋激发进行了表征。此外，课题组发现自旋冕面可以作为纳米级平台，通过尖端操纵来实现自旋1/2的反铁磁海森堡链。他们的发现提出了一种用多自由基制造冠状体的设计策略，这可能为制造开壳冠状体或循环自旋电子系统提供灵感。

据介绍，由于在全主题循环系统中自旋之间的强相互作用，从开壳冕状体中获得的多自由基在自旋电子学和量子技术中具有应用前景。由于纳米石墨烯的环化，日冕的合成一直被认为是困难的。由于自由基只有在大环尺寸超过临界值时才会出现，因此开壳冠状体的合成是一个巨大的挑战。

附：英文原文

Title: Collective Magnetism of Spin Coronoid via On-Surface Synthesis

Author: Xujie Zhu, Yashi Jiang, Zhou Wang, Yicheng Huang, Zhengqiang Luo, KaKing Yan, Shiyong Wang, Ping Yu

Issue&Volume: March 18, 2025

Abstract: Polyradicals obtained from open-shell coronoids hold promise for applications in spintronics and quantum technologies due to the strong interactions between spins in fully fused cyclic systems. Coronoid synthesis has long been considered difficult due to the cyclization of nanographene. It becomes an immense challenge to synthesize open-shell coronoids since radicals appear only  when the macrocycle size exceeds a critical value. Here we present an open-shell coronoid with six radicals achieved through an on-surface synthesis. This spin coronoid displays a collective spin state arising from both the nearest-neighbor exchange interaction and the next-nearest-neighbor exchange interaction of six unpaired π electrons along the conjugation pathways. The characterization of the spin excitation from the ground state to the excited state was carried out by using inelastic electron tunneling spectroscopy. Additionally, we show that the spin coronoid can be utilized as a nanoscale platform to achieve short antiferromagnetic spin-1/2 Heisenberg chains through tip manipulation. Our findings present a design strategy for creating coronoids with polyradicals, which could provide inspiration for fabrication of open-shell coronoid or cyclic spintronic systems.

DOI: 10.1021/jacs.4c13998

Source: https://pubs.acs.org/doi/abs/10.1021/jacs.4c13998