Critical effects in the reversible, nonlinear susceptibility ofPdMn spin glasses

The ac susceptibility of two PdMn spin glasses containing 5.0 and 5.5 at. % Mn have been measured as a function of temperature in a large number of static biasing fields between 0 and 500 Oe in the vicinity of the spin-glass (SG) temperature TSG. Our analysis of the field dependence of these data both above and below TSG provides the first experimental observation of a nearly symmetric divergence in the coefficients of the leading terms in H² and H⁴ in the nonlinear reversible susceptibility as T approaches TSG from above and below. The exponents which characterize the temperature dependence of the divergences are in good agreement with estimates obtained above TSG by other authors.