Magnetic domain wall energy in Ni/Co superlattices

The magnetic domain wall energy density σ_W of a Ni/Co superlattice possessing perpendicular magnetic anisotropy was determined using the magnetic domain theory derived by Kooy and Enz (1960). To determine σ_W, we obtained the saturation magnetization, magnetic domain period, and perpendicular magnetic anisotropy energy by individual measurements. Using the magnetic domain period and the ferromagnetic layer thickness, we first determined the dipolar length. The estimated dipolar length was about 15–25 nm, which is in good agreement with the change in the magnetization curve with the ferromagnetic layer thickness. By using the dipolar length and saturation magnetization, the σ_W was calculated to be 4–7 erg/cm². - Highlights: • Magnetic domain wall energy of a Ni/Co superlattice was determined experimentally. • The magnetic domain wall energy was estimated to be 4–8 erg/cm². • Using estimated value, the magnetization curves were reproduced well. • The estimated value is reasonable compared with the other ferromagnetic materials