Time Decay of the Remanent Magnetization in Spin-Glasses

Abstract

The time decay of the thermoremanent magnetization (${\ensuremath{\sigma}}_{\mathrm{TRM}}$) has been measured in 1.0% Cu: Mn and 2.6% Ag: Mn spin-glasses. It is shown that ${\ensuremath{\sigma}}_{\mathrm{TRM}}$ is neither an algebraic nor a logarithmic function of time, but it is found that ${\ensuremath{\sigma}}_{\mathrm{TRM}}$ can be characterized by a "stretched" exponential: ${\ensuremath{\sigma}}_{\mathrm{TRM}}={\ensuremath{\sigma}}_{0}\mathrm{exp}[\ensuremath{-}\frac{C{(\ensuremath{\omega}t)}^{1\ensuremath{-}n}}{(1\ensuremath{-}n)}]$. Similar time dependences appear in the disorder-diffusion theory of Grassberger and Procaccia and the cooperative-relaxation theory of Ngai, but neither theory in its present form is directly applicable to spin-glasses.