论文标题
Moiré调制晶格应变和厚度依赖性的晶格扩展PDTE $ _2 $
Moiré Modulated Lattice Strain and Thickness-Dependent Lattice Expansion in Epitaxial Ultrathin Films of PdTe$_2$
论文作者
论文摘要
我们报告了PDTE $ _2 $ Ultrathin Films在拓扑绝缘子BI $ _2 $ SE $ _3 $上的外延增长。在STM测量中观察到了突出的Moiré模式。随着膜厚度的减小，Moiré周期性增加，表明晶格的外观pdte $ _2 $薄膜的晶格扩展，厚度较低。此外，我们基于Moiré计量的模拟显示了PDTE $ _2 $域边缘的单轴晶格菌株，以及整个MoiréSuperCell的各向异性应变分布，晶格变化的净变化高达约2.9％。我们的DFT计算表明，这种应变效应会导致频带间隙在费米级附近的$γ$点的变窄。在约2.8％的应变下，$γ$的频段间隙完全关闭。进一步增加晶格应变会使带隙重新打开，并在能量倒置的传导带和价带的顺序。结果提供了在Moiré电位调节下构建拓扑材料量子网格的概念证明。
We report the epitaxial growth of PdTe$_2$ ultrathin films on topological insulator Bi$_2$Se$_3$. A prominent Moiré pattern was observed in STM measurements. The Moiré periodicity increases as film thickness decreases, indicating a lattice expansion of epitaxial PdTe$_2$ thin films with lower thicknesses. In addition, our simulations based on Moiré Metrology reveal uniaxial lattice strains at the edge of PdTe$_2$ domains, and anisotropic strain distributions throughout the Moiré supercell with a net change in lattice strain up to ~2.9%. Our DFT calculations show that this strain effect leads to a narrowing of the band gap at $Γ$ point near the Fermi level. Under a strain of ~2.8%, the band gap at $Γ$ closes completely. Further increasing the lattice strain makes the band gap reopen and the order of conduction band and valence bands inverted in energy. The results offer a proof of concept for constructing quantum grids of topological materials under the modulation of Moiré potentials.
