Exploring novel phase of matter is not only an essential research focus, but also an indispensable pathway toward the discovery of intriguing quantum physics and phenomena in the condensed matter physics. Over past few years, topological quantum materials, for example, topological superconductor has received significant attention because of its importance in fundamental science as well as technology applications ranging from spintronics to quantum computation.

Introducing magnetism to a 2D topological insulator that becomes a central issue in the pursuit of magnetic topological materials with a low-dimensionality. Since there are time-reversal symmetry broken and an exchange gap opened at the Dirac cone when spontaneous magnetization is present, the quantum anomalous Hall effect (QAHE) can be realized at zero magnetic field in the magnetic topological insulators. Stanene, the tin (Sn) analogue of graphene with a 2D honeycomb lattice, has been predicted to be a promising 2D topological insulator because of a strong spin-orbit coupling (SOC) from heavy atomic mass of Sn atom. 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 STM. Increases of both remanence to saturation magnetization ratio (Mr/Ms) and coercive field (Hc) 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 SOC-induced gap about 0.25 eV at the  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.