Thickness-tunable magnetic and electronic transport properties of the quasi-two-dimensional van der Waals ferromagnet Co0.27TaS2 with disordered intercalation

The intercalation of magnetic elements in non-magnetic van der Waals (vdW) materials is an effective way to design novel (quasi) 2D magnets and produce exotic properties. More specifically, how exactly the intercalator is distributed within the synthetic crystal can also affect the physical properties substantially. In contrast to conventional 3d transition-metal intercalates of niobium and tantalum dichalcogenides, which commonly have 2 × 2- or Ö3 × Ö3- type ordered intercalation, we report a disordered intercalation of Co atoms between the vdW gaps of 2H-tantalum disulfide (2H-TaS2). The obtained quasi-vdW ferromagnet Co0.27TaS2 shows both perpendicular magnetic anisotropy and thickness-tunable magnetic properties. More interestingly, the temperature dependence of electrical resistivity shows a semiconductor-like behavior, in contrast to the metallic feature of other analogs in this material family. This unexpected phenomenon can be understood through a variable-range hopping mechanism, which is due to highly disordered intercalation. Moreover, Co0.27TaS2 shows a side-jump scattering dominated anomalous Hall effect, which can also be related to the disordered distribution of Co intercalators.