Department of Physics, National Tsing Hua University, 300044 Hsinchu, Taiwan.
Department of Electrophysics, National Yang Ming Chiao Tung University, Hsinchu, 300093, Taiwan.
ACS Nano. 2023 Apr 25;17(8):7456-7465. doi: 10.1021/acsnano.2c12144. Epub 2023 Apr 4.
Introducing magnetism to two-dimensional topological insulators is a central issue in the pursuit of magnetic topological materials in low dimensionality. By means of low-temperature growth at 80 K, we succeeded in fabricating a monolayer stanene on Co/Cu(111) and resolving ferromagnetic spin contrast by field-dependent spin-polarized scanning tunneling microscopy (SP-STM). Increases of both remanence to saturation magnetization ratio (/) and coercive field () due to an enhanced perpendicular magnetic anisotropy (PMA) are further identified by out-of-plane magneto-optical Kerr effect (MOKE). In addition to ultraflat stanene fully relaxed on bilayer Co/Cu(111) from density functional theory (DFT), characteristic topological properties including an in-plane s-p band inversion and a spin-orbit coupling (SOC) induced gap about 0.25 eV at the Γ̅ point have also been verified in the Sn-projected band structure. Interfacial coupling of single-atomic-layer stanene with ferromagnetic Co biatomic layers allows topological band features to coexist with ferromagnetism, facilitating a conceptual design of atomically thin magnetic topological heterostructures.
将磁性引入二维拓扑绝缘体是追求低维磁性拓扑材料的核心问题。通过在 80 K 的低温生长，我们成功地在 Co/Cu(111)上制备了单层碲烯，并通过磁场依赖的自旋极化扫描隧道显微镜（SP-STM）解决了铁磁自旋对比。通过面外磁光克尔效应（MOKE）进一步确定了由于增强的垂直各向异性磁各向异性（PMA）而导致的剩磁与饱和磁化强度比（/）和矫顽力（）的增加。除了从密度泛函理论（DFT）得到的双层 Co/Cu(111)上完全弛豫的超平坦碲烯外，在 Sn 投影能带结构中还验证了包括平面 s-p 带反转和自旋轨道耦合（SOC）诱导的约 0.25 eV 的 Γ̅ 点间隙在内的特征拓扑性质。单原子层碲烯与铁磁 Co 双原子层的界面耦合允许拓扑带特征与铁磁性共存，从而促进了原子层磁拓扑异质结构的概念设计。
