Tuning the Structural and Magnetic Properties in Mixed Cation Mn_xCo_2–xP₂S₆

The metal thiophosphates (MTP), M2P2S6, are a versatile class of van der Waals materials, which are notable for the possibility of tuning their magnetic properties with the incorporation of different transition-metal cations. Further, they also offer opportunities to probe the independent and synergistic role of the magnetically active cation sublattice when coupled to P2Q6 polyhedra. Herein, we report the structural, magnetic, and electronic properties of the series of MTPs, MnxCo2–xP2S6 (x = 0.25, 0.5, 1, 1.5, 1.75) synthesized by the P2S5 flux method. Structural and elemental analysis indicates a homogeneous stoichiometry in the MnxCo2–xP2S6 compounds. We observe that a correlation is apparent between the intensities of specific Raman modes and Raman shifts with respect to the alloying ratio between Mn and Co. Magnetic susceptibility measurements indicate that the alloyed systems adopt an ordered antiferromagnetic (AFM) configuration with a dependence of the Néel temperature on the alloying ratio. A possible magnetic frustration behavior was observed for the composition MnCoP2S6 due to magnetic moment compensation as the alloying ratio between Mn and Co approaches parity. Interestingly, mixed oxidation states of the metal cation species are also observed in MnxCo2–xP2S6 along with a linear dependence of the work function on the alloying ratio of Mn and Co.