Influence of temperature on thermal relaxation of exchange bias field in CoFe/Cu/CoFe/IrMn spin valve

A multilayered spin valve film with a structure of Ta (5 nm)/Co₇₅Fe₂₅(5 nm)/Cu(2.5 nm)/Co₇₅Fe₂₅(5 nm)/Ir₂₀Mn₈₀ (12 nm)/Ta(8 nm) is prepared by the high-vacuum direct current (DC) magnetron sputtering. The effect of temperature on the spin valve structure and the magnetic properties are studied by x-ray diffraction (XRD), atomic force microscopy (AFM), and vibrating sample magnetometry. The effect of temperature on the exchange bias field thermomagnetic properties of multilayered spin valve is studied by the residence time of samples in a reverse saturation field. The results show that as the temperature increases, the IrMn (111) texture weakens, surface/interface roughness increases, and the exchange bias field decreases. Below 200 ℃, the exchange bias field decreases with the residence time increasing, and at the beginning of the negative saturation field, the exchange bias field H_ex decreases first quickly and then slowly gradually. When the temperature is greater than 200 ℃, the exchange bias field is unchanged with the residence time increasing.