Domain Wall Structure In [Pt(5(?))/Co(4(?))]_n/NiO(11(?))/[Co(4(?))/Pt(5(?))]_n Multilayers

The Co/Pt multilayers with perpendicular anisotropy are the potential and promising elements in design of perpendicular high density storage media, It have stimulated increasing interests. Domain structure has been studied using the magnetic force microscopy (MFM) and Magnetization measurements were performed at room temperature using the vibrating sample magnetometry (VSM) in the paper.The results show that in the antiferromagnetically coupled [Pt(5 A|。)/Co(4 A|。)]n/NiO(11 A|。)/[Co(4 A|。)/Pt(5 A|。)]n multilayers with perpendicular anisotropy, the antiferromagnetic interlayer coupling strength Jiec increases linearly with the repetition number n in the Co/Pt multilayer. In the demagnetized states, relatively shifted domain walls in the two c were observed with net ferromagnetic stripes formed between them for the repetition number n less than 5. The width of the net ferromagnetic stripes monotonic decrease with the repetition number n. In antiferromagnetically coupled [Pt(5 A|。)/Co(4 A|。)]4/NiO(11 A|。)/[Co(4 A|。)/Pt(5 A|。)]4 multilayer with perpendicular anisotropy, Along the initial magnetization curve, the magnetic reversal of the top multilayer is mainly due to domain nucleation at fields lower than the reversal field, while around the reversal field, growth of nucleated domains dominates. Along the field-decreasing branch in minor loop of the top Co/Pt multilayer, the magnetic reversal is through simultaneous domain nucleation and growth of nucleated domains, while along the field-increasing branch, the reversal is via domain nucleation at lower fields but via growth of nucleated domains around the reversal field. net ferromagnetic stripes are created in demagnetized state between the relatively shifted domain walls in the two Co/Pt multilayers owing to the competition between magnetostatic and exchange energies. With an external field applied antiparallel to the wall magnetization, involvement of Zeeman energy of net ferromagnetic stripes in the competition makes the net ferromagnetic stripes shrink, and the stripe width varies with field in an inversely proportional way in the low field range.