Transition from spin glass to paramagnetism in the magnetic properties of PrAu₂Si₂

It is unexpected that a spin-glass (SG) transition, which generally occurs only in systems with some form of disorder, was observed in the ThCr2Si2-type compound PrAu2Si2 at a temperature of ∼3 K. This puzzling phenomenon was later explained based on a novel dynamic frustration model that does not involve static disorder. We present the results of re-verification of the reported SG behaviors by measuring the physical properties of three polycrystalline PrAu2Si2 samples annealed under different conditions. Indeed, in the sample annealed at 827 °C for one week, a SG transition does occur at a temperature of T f ∼2.8 K as that reported previously in the literature. However, it is newly found that the SG effect is actually more pronounced in the as-cast sample, and almost completely disappears in the well-annealed (at 850 °C for four weeks) sample. The annealing effect observed in PrAu2Si2, that is, SG to paramagnetism transition is discussed by comparing with earlier results reported on the same system and other isomorphic compounds.