Thermal behavior of the interlayer coupling in a spin-valve Co/Pt multilayer with perpendicular anisotropy

In the spin-valve Co(4 Å)/Pt(36 Å)/[Co(4 Å)/Pt(6 Å)]2 multilayer with perpendicular anisotropy, with the decrease in temperature from 300 to 20 K, our investigations have revealed one transition of the interlayer coupling from antiferromagnetic to ferromagnetic through the Pt spacer at the temperature close to 80 K. Above 80 K, the obtained positive minor-loop shift displays a nonmonotonic variation with temperature, while below 80 K, the obtained negative minor-loop shift demonstrates a fast decrease in magnitude with temperature until a square hysteresis major loop is observed at 20 K. This observed unusual temperature behavior of the interlayer coupling can be attributed to the thermal variations in the magnetization of the bottom Co single layer and the polarization of the Pt spacer with temperature.