How thin a spin glass is still a spin glass?

The quasistatic spin-freezing temperature ${\mathit{T}}_{\mathit{f}}$ of thin layers of CuMn and AgMn remains nonzero down to thicknesses ${\mathit{W}}_{\mathrm{SG}}$ of 1 and 2 monolayers, respectively. These alloys thus remain spin glasses at such layer thicknesses, in agreement with published evidence of similar behavior for a two-dimensional, short-range, insulating spin glass. For ${\mathit{W}}_{\mathrm{SG}}$≤5 monolayers, we find ${\mathit{T}}_{\mathit{f}}$∝${\mathit{W}}_{\mathrm{SG}}^{\mathit{a}}$ as predicted by Fisher and Huse, with an exponent a=0.8±0.1.