Reentrant spin glass ordering in an Fe-based bulk metallic glass

We report the results of the complex susceptibility, temperature, and field dependence of DC magnetization and the nonequilibrium dynamics of a bulk metallic glass Fe₄₀Co₈Cr₁₅Mo₁₄C₁₅B₆Er₂. Solid indication of the coexistence of reentrant spin glass (SG) and ferromagnetic orderings is determined from both DC magnetization and AC susceptibility under different DC fields. Dynamics scaling of AC susceptibility indicates critical slowing down to a reentrant SG state with a static transition temperature T_s = ∼17.8 K and a dynamic exponent zv = ∼7.3. The SG nature is further corroborated from chaos and memory effects, magnetic hysteresis, and aging behavior. We discuss the results in terms of the competition among random magnetic anisotropy and exchange interactions and compare them with simulation predictions.