Self-assembly of magnetic Co atoms on stanene

We have investigated magnetic Co atoms self-assembled on ultraflat stanene on Cu (111) substrate by utilizing scanning tunneling microscopy/spectroscopy (STM/STS) in conjunction with density functional theory (DFT). By means of depositing Co onto the stanene/Cu (111) held at 80 K, Co atoms have developed into monomer, dimer, and trimer structures containing one, two, and three Co atoms, respectively. As per atomically resolved topographic images and bias-dependent apparent heights, the atomic structure models based on Sn atoms substituted by Co atoms have been deduced, which are in agreement with both self-consistent DFT calculations and STM simulations. Apart from that, the projected density of states has revealed a maximum at around -0. 5 eV from the Co-3d₃ₙ^{2-r^2} minority band, which contributes predominately to the peak feature at about -0. 3 eV in tunneling conductance (dI/dU) spectra taken at the Co atomic sites. As a result of the exchange splitting between the Co-3d majority and minority bands, there are nonzero magnetic moments, including about 0. 60₁ in monomer, 0. 56₁ in dimer, and 0. 29₁ in trimer of the Co-atom assembly on the stanene. Such a magnetic Co-atom assembly, therefore, could provide the vital building blocks to stabilize the local magnetism on two-dimensional stanene with nontrivial topological properties.