Fractional Spinon Quasiparticles in Open-Shell Triangulene Spin-1/2 Chains

• DOI: 10.1021/jacs.4c14712
• Publication Date: 2025-01-28T21:14:41Z
• Authors: Zhangyu Yuan; Xin-Yu Zhang; Yashi Jiang; Xiangjian Qian; Ying Wang; Yufeng Liu; Liang Liu; Xiaoxue Liu; Dandan Guan; Yaoyi Li; Hao Zheng; Canhua Liu; Jinfeng Jia; Mingpu Qin; Pei-Nian Liu; Deng-Yuan Li; Shiyong Wang
• Keywords: Spinon; Open shell

The emergence of spinon quasiparticles, which carry spin but lack charge, is a hallmark collective quantum phenomena in low-dimensional systems. While the existence spinons has been demonstrated through scattering spectroscopy ensemble samples, real-space imaging these quasiparticles within individual chains remained elusive. In this study, we construct Heisenberg antiferromagnetic spin-1/2 using open-shell [2]triangulene molecules as building blocks. Each unit, owing to its sublattice imbalance, hosts net accordance with Lieb's theorem, and spins are antiferromagnetically coupled covalent coupling strength J = 45 meV. Through scanning tunneling microscopy spectroscopy, probe states, excitation gaps, their spatial weights varying lengths atomic precision. Our investigation reveals that gap decreases chain length increases, extrapolating zero for long chains, consistent Haldane's gapless prediction. Moreover, inelastic an m-shaped energy dispersion characteristic confined one-dimensional box. These findings establish promising strategy exploring unique properties broad implications information.