  1T-TaS$_2$ is a prototypical charge-density-wave (CDW) system with a Mott
insulating ground state. Usually, a Mott insulator is accompanied by an
antiferromagnetic state. However, the antiferromagnetic order had never been
observed in 1T-TaS$_2$. Here, we report the stabilization of the
antiferromagnetic order by the intercalation of a small amount of Fe into the
van der Waals gap of 1T-TaS$_2$, i.e. forming 1T-Fe$_{0.05}$TaS$_2$. Upon
cooling from 300~K, the electrical resistivity increases with a decreasing
temperature before reaching a maximum value at around 15~K, which is close to
the Neel temperature determined from our magnetic susceptibility measurement.
The antiferromagnetic state can be fully suppressed when the sample thickness
is reduced, indicating that the antiferromagnetic order in Fe$_{0.05}$TaS$_2$
has a non-negligible three-dimensional character. For the bulk
Fe$_{0.05}$TaS$_2$, a comparison of our high pressure electrical transport data
with that of 1T-TaS$_2$ indicates that, at ambient pressure, Fe$_{0.05}$TaS$_2$
is in the nearly commensurate charge-density-wave (NCCDW) phase near the border
of the Mott insulating state. The temperature-pressure phase diagram thus
reveals an interesting decoupling of the antiferromagnetism from the Mott
insulating state.
