Stabilization of antiferromagnetism in 1T-Fe_0.05TaS₂

1T-TaS₂ is a prototypical charge-density-wave system with a Mott insulating ground state. Usually, a Mottinsulator is accompanied by an antiferromagnetic state. However, the antiferromagnetic order had never beenobserved in 1T-TaS₂. Here, we report the stabilization of the antiferromagnetic order by the intercalation ofa small amount of Fe into the van der Waals gap of 1T-TaS₂, i.e., forming 1T-Fe_0.05TaS₂. Upon cooling from300 K, the electrical resistivity increases with a decreasing temperature before reaching a maximum value ataround 15 K, which is close to the Néel temperature determined from our magnetic susceptibility measurement.The antiferromagnetic state can be fully suppressed when the sample thickness is reduced, indicating that theantiferromagnetic order in Fe_0.05TaS₂ has a non-negligible three-dimensional character. For the bulk Fe_0.05TaS₂, acomparison of our high pressure electrical transport data with that of 1T-TaS₂ indicates that, at ambient pressure,Fe_0.05TaS₂ is in the nearly commensurate charge-density-wave phase near the border of the Mott insulating state.The temperature-pressure phase diagram thus reveals an interesting decoupling of the antiferromagnetism fromthe Mott insulating state.