Evidence of Ferromagnetic Clusters and Griffiths Singularity in Magnetic Weyl Semimetal Co$ _{3} $Sn$ _{2} $S$ _{2} $

Abstract

Cobalt based sulphides of compositional formula Co3A2S2 (A = Sn and In) are endowed with frustrated kagome lattice structure and a plethora of novel phenomena determined from the topological band structure. Here-in, we report on the detailed exploration of anisotropic magnetic properties of single crystals of ferromagnetic compound Co3Sn2S2. A low temperature clustered-glassy magnetic behaviour is revealed in field-cooled and zero field-cooled magnetization and memory effect measurement protocols. The sharp downturn and non-linearity observed in the inverse susceptibility above the critical temperature TC in the paramagnetic region corroborates to the presence of short-range ferromagnetic clusters above TC in Co3Sn2S2. The deviation from linear Curie-Weiss behaviour in the paramagnetic state signifies the strong Griffiths singularity in the material. The slow spin dynamics behaviour and zero spontaneous magnetization above TC give an evidence of Griffiths phase owing to the ferromagnetic clusters. The magnetic hysteresis loops represent the magnetization reversal which, in turn, also indicate the short range magnetic correlations, and reflect the coexistence of hard and soft magnetic phases in Co3Sn2S2. The Arrott plots derived from magnetization reveal convex type curvature at low fields and linear positive behaviour in the high field region, confirming the second order magnetic phase transition in Co3Sn2S2. The Takahashi spin fluctuation theory analysis provides a sufficient evidence for itinerant ferromagnetism in Co3Sn2S2. A large magnetocrystalline anisotropy concomitant with a high anisotropy field suggests the dominance of strong spin orbit coupling phenomenon. Our experimental results emphasize an intuitive understanding of the complex nature of magnetism present in Co-based shandite systems.