Survey of Sn and S Surface Terminations and Sulfur Migration on Co₃Sn₂S₂ With Experimental STM Measurements

Co₃Sn₂S₂ is a kagome magnet Weyl semimetal with Fermi arc contours and Weyl node connectivity that is directly influenced by its three surface terminations. Using Scanning Tunneling Microscopy (STM), we investigate the two most common surface terminations, the Sn and S surfaces for their termination boundaries and defect sites. As a result of the Sn-Sn bonding and distance between the Sn and the S layers, partial cleaving terminations can occur with variable coverage of Sn vacancies on the Sn surface and Sn adatoms on the S surface. Along with vacancies and adatoms, the boundary between Sn and S surfaces transition with intermediate zones that have changing S and Sn coverage before converging into one surface [1]. We aim to study the Sn termination face in detail for the density of vacancies and their configurations around defect sites, as well as the length scale and other features of the termination transitions. Additionally observations of the S sites for possible migration behavior as a function of time and temperature will be conducted.

[1] Yin et al, Nature Physics 15, 444 (2019).