Yuan Zhangyu, Zhang Xin-Yu, Jiang Yashi, Qian Xiangjian, Wang Ying, Liu Yufeng, Liu Liang, Liu Xiaoxue, Guan Dandan, Li Yaoyi, Zheng Hao, Liu Canhua, Jia Jinfeng, Qin Mingpu, Liu Pei-Nian, Li Deng-Yuan, Wang Shiyong
Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), TD Lee Institute, School of Physics and Astronomy, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China.
School of Chemistry and Molecular Engineering, East China University of Science & Technology, Shanghai 200237, China.
J Am Chem Soc. 2025 Feb 12;147(6):5004-5013. doi: 10.1021/jacs.4c14712. Epub 2025 Jan 28.
The emergence of spinon quasiparticles, which carry spin but lack charge, is a hallmark of collective quantum phenomena in low-dimensional quantum spin systems. While the existence of spinons has been demonstrated through scattering spectroscopy in ensemble samples, real-space imaging of these quasiparticles within individual spin chains has remained elusive. In this study, we construct individual Heisenberg antiferromagnetic spin-1/2 chains using open-shell [2]triangulene molecules as building blocks. Each [2]triangulene unit, owing to its sublattice imbalance, hosts a net spin-1/2 in accordance with Lieb's theorem, and these spins are antiferromagnetically coupled within covalent chains with a coupling strength of J = 45 meV. Through scanning tunneling microscopy and spectroscopy, we probe the spin states, excitation gaps, and their spatial excitation weights within covalent spin chains of varying lengths with atomic precision. Our investigation reveals that the excitation gap decreases as the chain length increases, extrapolating to zero for long chains, consistent with Haldane's gapless prediction. Moreover, inelastic tunneling spectroscopy reveals an -shaped energy dispersion characteristic of confined spinon quasiparticles in a one-dimensional quantum box. These findings establish a promising strategy for exploring the unique properties of excitation quasiparticles and their broad implications for quantum information.
携带自旋但不带电荷的自旋子准粒子的出现，是低维量子自旋系统中集体量子现象的一个标志。虽然通过对系综样品的散射光谱已经证明了自旋子的存在，但在单个自旋链中对这些准粒子进行实空间成像仍然难以实现。在这项研究中，我们使用开壳层[2]三角烯分子作为构建单元构建了单个海森堡反铁磁自旋 - 1/2链。每个[2]三角烯单元由于其亚晶格不平衡，根据利布定理拥有一个净自旋 - 1/2，并且这些自旋在共价链内以J = 45毫电子伏特的耦合强度进行反铁磁耦合。通过扫描隧道显微镜和光谱学，我们以原子精度探测了不同长度共价自旋链内的自旋态、激发能隙及其空间激发权重。我们的研究表明，激发能隙随着链长的增加而减小，对于长链外推至零，这与霍尔丹的无隙预测一致。此外，非弹性隧道光谱揭示了一维量子盒中受限自旋子准粒子的 - 形能量色散特征。这些发现为探索激发准粒子的独特性质及其对量子信息的广泛影响建立了一个有前景 的策略。
