Annealing effect on interlayer exchange coupling in perpendicularly magnetized synthetic antiferromagnetic structure based on Co/Pd multilayers with ultrathin Ru spacer

Perpendicularly magnetized synthetic antiferromagnetic (p-SAF) structures exhibiting large exchange field (H-ex) values have been widely studied for application to spintronic devices. We investigated magnetic properties of p-SAF structures based on Co/Pd multilayers with an ultrathin Ru spacer at various annealing temperatures (T-a). The [Co/Pd]-based p-SAF structures exhibited large H-ex values of the order of kOe up to T-a = 350 degrees C. We clarified that H-ex in the p-SAF structures significantly degrades with increasing T-a mainly owing to a marked reduction in exchange coupling energy (J(ex)). These results demonstrate that [Co/Pd]-based p-SAF structures exhibit sufficiently large H-ex values for device applications and that the annealing stability is predominantly determined by J(ex). (C) 2018 The Japan Society of Applied Physics