Abstract
Topological materials hosting kagome lattices have drawn considerable attention due to the interplay between topology, magnetism, and electronic correlations. The (Fe1−xCox)Sn system not only hosts a kagome lattice but has a tunable symmetry-breaking magnetic moment with temperature and doping. In this study, angle-resolved photoemission spectroscopy and first-principles calculations are used to investigate the interplay between the topological electronic structure and varying magnetic moment from the planar to axial antiferromagnetic phases. Evidence for a theoretically predicted gap at the Dirac point is revealed in the low-temperature axial phase, but no gap opening is observed across a temperature-dependent magnetic phase transition. However, topological surface bands are observed to shift in energy as the surface magnetic moment is reduced or becomes disordered over time during experimental measurements. The shifting surface bands may preclude the determination of a temperature-dependent bulk gap, but this highlights the intricate connections between magnetism and topology with a surface/bulk dichotomy that can affect material properties and their interrogation.
