Emergent Griffiths-phase-like behavior in the ball-milled nanocrystalline Dy4RhAl and its implication

We report the results of dc susceptibility and heat capacity measurements on the (ball-milled) nanocrystalline rare-earth (R) ternary compound, crystallizing in Gd4RhIn type, cubic Dy4RhAl compound. The bulk form of this compound has been known to undergo antiferromagnetic ordering at (TN=) 18 K with concomitant cluster spin glass anomalies. The present studies on the nano-form obtained by ball milling reveal that this antiferromagnetic ordering is suppressed with the reduction of particle size with no feature attributable to a well defined long-range magnetic ordering down to 1.8 K, but showing an inhomogeneous magnetism below 10 K. The point being stressed is that the results show the dominance of a feature around 30 K in the magnetic susceptibility data (well above TN of the bulk form) mimicking Griffiths phase. We infer that surface magnetism dominates before long range magnetic ordering occurs in this material.