Magnetic domain structure of Fe-C/Ni-Fe multilayers with insertion of magnetic-decoupling BN layers, observed by spin-polarized SEM

Abstract The effects of the periodic insertion of nonmagnetic boron nitride (BN) layers on the magnetic domain structure of Fe-C/Ni-Fe magnetic multilayers have been investigated by spin-polarized scanning electron microscopy. The multilayers were prepared by ion beam sputtering and were lithographically patterned into 50 × 300 μm stripes. In Fe-C/Ni-Fe multilayered stripes whose easy axis direction is normal to the longitudinal direction of stripes, the closure domains disappeared with the insertion of a BN layer. However, in Fe-C/Ni-Fe multilayered stripes whose easy axis direction is parallel to the longitudinal direction of the stripes, an unusual domain pattern appeared, including triangular closure domains at the edge and magnetization ripple. This domain pattern may be understood in terms of the magnetoelastic effect of magneto-stress anisotropy.