Many spintronic devices such as thermally-assisted magnetic random access memories take advantage of the ferromagnetic(F)/antiferromagnetic(AF) interaction to pin the magnetization of a reference layer. However, they suffer from detrimental blocking temperatures distributions from memory cell to memory cell. A low-temperature contribution to the distribution was ascribed to spin-glass like regions which are randomly spread over the film. We report on an attempt to reduce the amount of these spin-glass like regions due to interdiffusion of species by adding a diffusion barrier at the F/AF interface.