Nonlinear dynamic susceptibilities at the spin-glass transition of Ag:Mn

We have measured the ac nonlinear susceptibilities χ₃', χ₅', and χ₇' of very dilute Ag:Mn spin-glasses above and below the transition temperature Tg as functions of frequency, temperature, and magnetic field. In the static limit, these quantities display well defined critical singularities at Tg. The nonlinear susceptibilities can be fitted above Tg by powers of frequency with weakly temperature-dependent exponents. While the effective exponents satisfy the relations imposed by static and dynamic scaling, the observed temperature and frequency roundings suggest the presence of additional length scales.