Griffiths-like phase in a Mn-Intercalated Dichalcogenide

Static and dynamic magnetic measurements have been performed on polycrystalline Mn_0.23TaS₂. The measurements indicate the presence of a Griffiths-like phase preceding the paramagnetic to ferromagnetic transition at 57 K. The transition temperature in the clean limit, i.e., for single-crystalline Mn_0.25TaS₂, is known to be 80 K. dc magnetization measurements on Mn_0.23TaS₂ indicate a magnetic field-dependent downturn in the inverse susceptibility as a function of temperature below 105 K, a key indicator of the existence of a Griffiths phase. The magnetization also exhibited power law behavior as a function of both temperature and field in this regime. The power-law exponent for M(H) varied with temperature in the Griffiths regime until the critical region was approached. At this point, a modified Arrott plot was necessary to describe the data, giving critical exponents close to the theoretical values for 3D Heisenberg magnets. The second-order ac susceptibility exhibited frequency-dependent peaks in the Griffiths region, which strongly suggests the formation of ordered clusters. The dc magnetization also exhibited logarithmic time decay. The evidence points to a robust Griffiths phase in Mn_0.23TaS₂.