  Magnetic topological materials, in which strong correlations between magnetic
and electronic properties of matter, give rise to various exotic phenomena such
as anomalous Hall effect (AHE), topological Hall effect (THE), and skyrmion
lattice. Here, we report on the electronic, magnetic, and topological
properties of Mn$_{3-\it{x}}$Fe$_{\it{x}}$Sn single crystals ($\it{x}$=0, 0.25,
and 0.35). Low temperature magnetic properties have been significantly changed
with Fe doping. Most importantly, we observe that large uniaxial
magnetocrystalline anisotropy that is induced by the Fe doping in combination
with competing magnetic interactions at low temperature produce nontrivial
spin-texture, leading to large topological Hall effect in the doped systems at
low temperatures. Our studies further show that the topological properties of
Mn$_{3-\it{x}}$Fe$_{\it{x}}$Sn are very sensitive to the Fe doping.
