Finite-size effects in Cu-Mn spin glasses

Finite-size effects in the spin glass (SG) Cu-Mn have been studied using magnetron-sputtered multilayer systems (MS’s) of the form ${\mathrm{Cu}}_{1\mathrm{-}\mathit{x}}$ ${\mathrm{Mn}}_{\mathit{x}}$/Cu and ${\mathrm{Cu}}_{1\mathrm{-}\mathit{x}}$ ${\mathrm{Mn}}_{\mathit{x}}$/Si with x=0.04, 0.07, 0.14 (and some data for 0.21). The SG layers have widths ${\mathit{W}}_{\mathrm{Cu}\mathrm{-}\mathrm{Mn}}$ ranging from 10 000 to 20 Å and are separated and magnetically decoupled from each other by interlayers of either 300 Å of Cu or 70 Å of Si. The MS’s continue to show SG peaks in the zero-field-cooled (ZFC) ‘‘dc’’ magnetic susceptibility χ down to ${\mathit{W}}_{\mathrm{Cu}\mathrm{-}\mathrm{Mn}}$=20 Å. The quasistatic freezing temperature ${\mathit{T}}_{\mathit{f}}$ (defined as the location of the peak in χ) begins to decrease from its bulk value, ${\mathit{T}}_{\mathit{f}}^{\mathit{b}}$, at ${\mathit{W}}_{\mathrm{Cu}\mathrm{-}\mathrm{Mn}}$≊1000 Å and approaches zero for SG thicknesses 0≤${\mathit{W}}_{\mathrm{Cu}\mathrm{-}\mathrm{Mn}}$≤10 Å with Cu interlayers or 30 Å≤${\mathit{W}}_{\mathrm{Cu}\mathrm{-}\mathrm{Mn}}$≤35 Å with Si interlayers.