Antisymmetric interlayer exchange coupling spontaneously built in synthetic antiferromagnetic structures using film growth

Abstract The antisymmetric-type long-range exchange interactions between two ferromagnetic layers through a nonmagnetic layer, called antisymmetric interlayer exchange coupling (AIEC), have recently been discovered and attracted much attention. This paper reports that AIEC is naturally built in synthetic antiferromagnets (SyAFs) depending on the thin-film growth conditions. For SyAFs comprising Pt/Co/Ir/Co/Pt layers, two kinds of film growth parameters are examined: the effects of epitaxial growth and oblique incident of sputter-deposition. The present results indicate that spatial fluctuations in thicknesses are one of the major sources inducing AIEC, whereas epitaxial growth, which leads to sharp interfaces and uniformity in layer thicknesses, effectively suppresses unexpected AIEC. In addition, the oblique sputter deposition provides large AIEC and anisotropic distribution of AIEC direction in the case of textured films. The findings in this study provide key factors for designing AIEC and are useful for developing emerging computing technologies with artificial three-dimensional topological magnetic structures.