Magnetic dynamics and magnetic domain formation of Co₂Ni/Si(100) films

Magnetic thin films with characteristics such as low switching energy of magnetization reversal accompanying perpendicular magnetic anisotropy are highly desirable for spintronic devices. Particularly, multilayers were extensively studied to produce an efficient spin torque switching with tunable perpendicular magnetic anisotropy. From the literature, the general research regarding magnetic dynamics and magnetic anisotropy by microwave-dependent magnetic measurements of Co/Ni in alloy form remains limited. Here we report on the magnetic dynamics and magnetic domain formation for Co₂Ni/Si(100). As the Co₂Ni thickness increases, magnetic domains change from random sizes to stripe shape at magnetic field close to the coercive field. By considering effective anisotropy energy and exchange stiffness constant, the critical thickness could be calculated to be around 19 nm that is comparable to experimental result of the occurrence of magnetic domains with a striped shape. The trend of the higher resonance magnetic fields for larger polar angle could be explained by the finding that the easy axis of magnetization is more preferred to the surface normal to the film. By considering the intrinsic damping contribution in the linewidth, the damping coefficient for Co₂Ni can be determined here and shows the inhomogeneity influencing the magnetization alignment in the films. Our research work on the magnetic dynamics of Co₂Ni may pave the way to further applications of magnetic alloy on microwave-based spintronic devices.