Abstract
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.
Highlights
Mott insulators are an important class of materials in strongly correlated electron research
The sustained interest in Mott insulators can be largely attributed to the fact that several distinct families of superconductors are found in their vicinity (e.g., Refs. [1,2,3,4,5,6])
Further analysis of our high pressure transport data shows that we can construct a universal temperaturepressure phase diagram for 1T-TaS2 and 1T-Fe0.05TaS2, where we find that the antiferromagnetism is detached from the Mott state
Summary
Mott insulators are an important class of materials in strongly correlated electron research. [1,2,3,4,5,6]) In these systems, the superconducting phase arises when the Mott insulating state is tuned away either by controlling the band filling or by varying the bandwidth. A Mott insulating phase in the twisted bilayer graphene can be driven into a superconducting state by electrostatic doping the bilayer graphene at a magic twist angle [5,6]. 1T-TaS2 is an interesting layered transition metal dichalcogenide featuring a series of charge-density-wave (CDW) transitions [7,8,9,10]. In the CCDW phase, the displacement of the Ta atoms in the layer forms clusters
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