Effect of film thickness on magnetic properties of Cr/SmCo/Cr films

Cr/SmCo/Cr films with different SmCo thickness were deposited on glass substrates by magnetron sputtering, followed by an annealing process at 550 °C for 20 min. Experimental results showed that the SmCo film of 30 nm exhibited two-phase behavior in the demagnetization process, the obvious kink was observed near zero. For the SmCo film of 50 nm, the kink was invisible, and a single phase like behavior was obtained in the demagnetization process. The reversal behavior became consistent in the thicker films. Moreover, the coercivity reduced and the saturated magnetization increased obviously with the increasing thickness. X-ray diffraction results indicated that the average grain size of SmCo5 in the thicker films were almost 30 nm, but the quantity of SmCo5 grains increased with the increasing thickness, which enhanced the intergrain exchange coupling (IEC) of the SmCo5 hard phases. The increase of IEC improved the magnetic properties of SmCo films with increasing thickness.