  Topological materials hosting kagome lattices have drawn considerable
attention due to the interplay between topology, magnetism, and electronic
correlations. The (Fe$_{1-x}$Co$_x$)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. 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 highlights the intricate connections between
magnetism and topology with a surface/bulk dichotomy that can affect material
properties and their interrogation.
