Thickness-dependence of magnetic anisotropy and domain structure in Ni thin films grown on a PMN-PT substrate

High-quality Ni ferromagnetic thin films with the thicknesses of 180, 240, 330, and 510 nm +/- 5 nm were grown on (001)Pb(Mg1/3Nb2/3)(0.7)Ti0.3O3(PMN-PT) single-crystal substrates by magnetron sputtering followed by annealing. The thickness dependence of magnetic anisotropy was investigated using ferromagnetic resonance, indicating that the 180 nm Ni thin film exhibits a large magnetic anisotropy field. Increasing the film's thickness resulted in a reduction of the magnetic anisotropy. Well-defined stripe domain structures in Ni thin films were observed. Calculations based on the tilted partial flux closure domain structure with Bloch wall and Neel wall indicate an increase in the primary domain size and closure domain size of Ni thin films with increasing film thickness.