Theory of freezing temperatures of metallic spin glass multilayers

A mean field approach is used to calculate the freezing temperature T_g in metallic spin glass multilayer systems. We calculate the dependence of T_g( W_SG) on the thickness W_SG of spin glass layers separated by metallic interlayers of thickness W_il large enough that the spin glass layers are not coupled to one another. We also calculate the dependence of T_g( W_il) on W_il for the case where W_il is small enough to allow coupling between the spin glass layers. Theoretical results are in good agreement with experimental data. Finite-temperature effects, scattering of electrons by nonmagnetic impurities, and intrinsic sd scattering of electrons by the spins play important roles in establishing the trends exhibited by T_g( W_SG) and T_g( W_il). A clear physical interpretation is given which explains the behaviours of T_g( W_SG) and T_g( W_il) in experimental spin glass multilayers. We also predict how T_g( W_SG) and T_g( W_il) will behave if the nonmagnetic impurity concentration is nonnegligible.