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

It is unexpected that a spin-glass transition, which generally occurs only in system 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 spin-glass 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 spin-glass 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 spin-glass effect is actually more pronounced in the as-cast sample, and almost completely disappears in the well-annealed (at 850 ◦C for 4 weeks) sample. The annealing effect observed in PrAu2Si2, that is, spin glass to paramagnetism transition is discussed by comparing with earlier results reported on the same system and other isomorphic compounds.