Indium-decorated Si atomic chains on a stepped Si(553)–Au substrate are proposed as an extended Su–Schrieffer–Heeger (SSH) model, revealing topological end states. An appropriate amount of In atoms on the Si(553)–Au surface induce the self-assembly formation of trimer SSH chains, where the chain unit cell comprises one In atom and two Si atoms, confirmed by scanning tunneling microscopy images and density functional calculations. The electronic structure of the system, examined through scanning tunneling spectroscopy, manifests three electron bands within the Si–In chain, accompanied by additional midgap topological states exclusively appearing at the chain’s end atoms. To elucidate the emergence of these topological states, a tight-binding model for a finite-length-extended SSH chain is proposed. Analysis of the energy spectra, density of states functions, and eigenfunctions demonstrates the topological nature of these self-assembled atomic chains.

中文翻译：

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Su-Schrieffer-Heeger 模型在 Si(553)-Au 表面自组装 Si-In 原子链中的实现


阶梯式 Si(553)-Au 衬底上的铟修饰的 Si 原子链被提出作为扩展的 Su-Schrieffer-Heeger (SSH) 模型，揭示了拓扑最终状态。通过扫描隧道显微镜图像和密度泛函计算证实，Si(553)-Au表面上适量的In原子诱导三聚体SSH链的自组装形成，其中链晶胞包含一个In原子和两个Si原子。通过扫描隧道光谱检查系统的电子结构，显示出 Si-In 链内的三个电子带，并伴有仅出现在链末端原子的额外中带隙拓扑态。为了阐明这些拓扑状态的出现，提出了有限长度扩展 SSH 链的紧束缚模型。对能谱、态密度函数和本征函数的分析证明了这些自组装原子链的拓扑性质。