Origin of Stripe Domains in Ni–Fe Films

Abstract

Stripe domains have been observed in Ni–Fe films having positive, zero, or negative magnetostriction and with either tensile or compressive stress. By using the model of Saito et al. and assuming their anisotropy constant K is attributed to both the shape anisotropy K0 and the magnetostrictively induced anisotropy Ks, we can explain our experimental results quantitatively. Here K0 and Ks are determined from the stress, the magnetostriction and the geometry of a columnar grain structure (defined by Iwata et al.). From a critical thickness (the minimum thickness above which the stripe domains will be formed) vs film composition curve, it has been found that K0 is about an order of magnitude larger than Ks at a composition of 85% Ni. Therefore, the shape anisotropy, especially in the neighborhood of 81.7% Ni, is determined as the predominant factor in the perpendicular anisotropy which causes formation of stripe domains. Dependence of stripe domains on annealing, film thickness, substrate temperature, and vacuum pressure during film deposition further supports our conclusion.