Evolution of magnetic properties and domain structures in Co/Ni multilayers

Abstract

Co/Ni multilayers with different layer thicknesses and repetition numbers were fabricated by magnetron sputtering. The films with appropriate Co and Ni layer thicknesses show strong perpendicular magnetic anisotropy. The results of magnetic force microscopy indicate that the films show a maze domain in the demagnetization state and that the domain width decreases with increasing layer thickness and repetition number. The magnetostatic and domain wall energies of the film stack were calculated on the basis of an irregular maze domain pattern. The results suggest that the magnetostatic energy is the main reason for the variation of the domain width in Co/Ni multilayers.

Impact of growth conditions on the domain nucleation and domain wall propagation in Pt/Co/Pt stacks

“…The magnetization loops for Series A (figure 4(a)) show that the coercive field increases with increasing thickness. This in agreement with the results of Metaxas et al [9] on Pt/Co/Pt, but opposite to what Su et al [29] obtained for Co/Ni stacks, which suggests that this behavior is material-dependent. In addition, figure 4(b) demonstrates that DW velocity changes dramatically with the Co thickness: the DW velocity at 15 Oe is 2.5 × 10 −3 m s −1 for the d Co = 0.41 nm sample against 1.1 × 10 −7 m s −1 for the d Co = 0.52 nm sample.…”

Impact of growth conditions on the domain nucleation and domain wall propagation in Pt/Co/Pt stacks

“…Regarding Series B, it was shown that Co thickness is strongly determinant for both the coercive field and the DW velocity. In particular, the increase of the coercive field with the Co thickness is in agreement with the work from Metaxas et al 14 on Pt/Co/Pt, and opposite to what Su et al 24 obtained for Co/Ni stacks. Finally, we have assessed the changes in DW motion due to base pressure modification (Series C).…”

The double-shifted magnetic hysteresis loops and domain structure in perpendicular [Co/Ni]N/IrMn exchange biased systems

“…To clarify this point, we investigated the domain structure in the Pt 10/(Co 03/Ni 0.4) N /IrMn (t IrMn )/Pt 2 structure with different N, as shown in figure 4. By changing the repetition number N, the intrinsic domain structure can be tuned due to the variation of the dipole energy [27]. The first row in figure 4 show the MFM images of (Co/Ni) N /IrMn with t IrMn = 10 nm.…”

“…Without considering the AFM layer, the domain size in the FM layer is determined by a balance of the dipolar energy and the domain wall energy, the former reduce domain size and the latter increase domain size. The balanced domain size is ~μm scale in (Co/Ni) N multilayers and increase with decreasing total thickness of FM layer or repetition number N [27]. Therefore, when an IrMn layer is deposited on the (Co/ Ni) N multilayers, a new balanced domain size was obtained to minimize the total energy in FM-AFM multilayer.…”