Self-Assembly of Magnetic Co Atoms on Stanene

TL;DR

This study explores the self-assembly, atomic structure, and magnetic properties of Co atoms on stanene, revealing their potential to stabilize local magnetism on 2D topological materials.

Contribution

It provides detailed atomic and magnetic characterization of Co atom assemblies on stanene, combining STM/STS and DFT, and highlights their potential in 2D magnetism.

Findings

Co atoms form monomers, dimers, and trimers on stanene.

Magnetic moments are observed in all Co assemblies.

Electronic structure shows spin polarization and specific density of states features.

Abstract

We have investigated the magnetic Co atoms self-assembled on the 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 the 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 (PDOS) has revealed a minimum at around -0.5 eV from the Co-3d3z2-r2 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 non-zero magnetic moments, including about 0.60 uB in monomer, 0.56 uB in dimer, and 0.29 uB in trimer of the Co atom assembly on the stanene. Such magnetic Co atom assembly therefore could provide the vital building blocks in stabilizing the local magnetism on the two-dimensional (2D) stanene with non-trivial topological properties.