  Kagome lattice hosts a plethora of quantum states arising from the interplay
of topology, spin-orbit coupling, and electron correlations. Here, we report
symmetry-breaking electronic orders tunable by an applied magnetic field in a
model Kagome magnet FeSn consisting of alternating stacks of two-dimensional
Fe3Sn Kagome and Sn2 honeycomb layers. On the Fe3Sn layer terminated FeSn thin
films epitaxially grown on SrTiO3(111) substrates, we observe trimerization of
the Kagome lattice using scanning tunneling microscopy/spectroscopy, breaking
its six-fold rotational symmetry while preserving the transitional symmetry.
Such a trimerized Kagome lattice shows an energy-dependent contrast reversal in
dI/dV maps, which is significantly enhanced by bound states induced by Sn
vacancy defects. This trimerized Kagome lattice also exhibits stripe
modulations that are energy-dependent and tunable by an applied in-plane
magnetic field, indicating symmetry-breaking nematicity from the entangled
magnetic and charge degrees of freedom in antiferromagnet FeSn.
