Consider 3 layers of Ferromagnetic materials stacked on top of each other with appropriate spacer layers in between. Let the top and bottom layers be pinned to layers of Anti Ferromagnets adjacent to them such that the magnetic moments of the top and bottom layers are anti parallel. The two spacer layers in between top & middle layer and bottom & middle layer have thicknesses such that the magnetic moment of the middle layer is anti parallel to the top and bottom layer mediated by the RKKY interaction. Since top and bottom layers are pinned to be anti parallel to each other, the middle layer is frustrated as it cannot be anti parallel to both the layers simultaneously. So in what direction does the magnetic moment of the middle layer get aligned?