Spin-glass behavior in PrAu2Si2

We have studied the magnetic properties of pure PrAu2Si2. The data show the characteristic features of a canonical spin glass with a freezing temperature of T-F=3 K. Thus, PrAu2Si2 is to OUT knowledge the first example of a pure rare-earth spin glass with well-localized magnetic moments and without any intentionally introduced disorder. Recently, Sullow ct al. [S. Sullow, G. J. Nieuwenhuys, A. A. Menowsky, J. A. Mydosh, S. A. M. Mentik, T. E. Mason, and W. J. L. Buyers, Phys. Rev. Lett. 78, 354 (1997)] discovered heavy-fermion spin-glass behavior in URh2Ge2. Our present results reveal that URh2Ge2 is not a unique case and that strong hybridization of the localized moments with the band states is not a necessary ingredient but that spin-glass behavior might be a much more widespread phenomenon in ternary RT2X2 (R=rare earth/U,T=transition metal,X=Si, Ge) compounds. However, the origin of the frustration, which is necessary to achieve a disordered ground state, still has to be elucidated in this new class of spin-glass compounds. [S0163-1829(99)50610-3].