Geng Daiyu, Zhou Hui, Yue Shaosheng, Sun Zhenyu, Cheng Peng, Chen Lan, Meng Sheng, Wu Kehui, Feng Baojie
Institute of Physics, Chinese Academy of Sciences, 100190, Beijing, China.
School of Physical Sciences, University of Chinese Academy of Sciences, 100049, Beijing, China.
Nat Commun. 2022 Nov 16;13(1):7000. doi: 10.1038/s41467-022-34043-9.
The Su-Schrieffer-Heeger (SSH) model in a two-dimensional rectangular lattice features gapless or gapped Dirac cones with topological edge states along specific peripheries. While such a simple model has been recently realized in photonic/acoustic lattices and electric circuits, its material realization in condensed matter systems is still lacking. Here, we study the atomic and electronic structure of a rectangular Si lattice on Ag(001) by angle-resolved photoemission spectroscopy and theoretical calculations. We demonstrate that the Si lattice hosts gapped Dirac cones at the Brillouin zone corners. Our tight-binding analysis reveals that the Dirac bands can be described by a 2D SSH model with anisotropic polarizations. The gap of the Dirac cone is driven by alternative hopping amplitudes in one direction and staggered potential energies in the other one and hosts topological edge states. Our results establish an ideal platform to explore the rich physical properties of the 2D SSH model.
二维矩形晶格中的Su-Schrieffer-Heeger（SSH）模型具有无隙或有隙的狄拉克锥，沿特定边缘具有拓扑边缘态。虽然这样一个简单的模型最近已在光子/声子晶格和电路中实现，但在凝聚态物质系统中的材料实现仍然缺乏。在这里，我们通过角分辨光电子能谱和理论计算研究了Ag(001)上矩形Si晶格的原子和电子结构。我们证明，Si晶格在布里渊区角点处存在有隙狄拉克锥。我们的紧束缚分析表明，狄拉克能带可以用具有各向异性极化的二维SSH模型来描述。狄拉克锥的能隙由一个方向上交替的跳跃幅度和另一个方向上交错的势能驱动，并具有拓扑边缘态。我们的结果建立了一个理想的平台，用于探索二维SSH模型丰富的物理性质。
