Aging mechanisms in amorphous GdTbFe films

In coated RE-TM-films the degradation of magnetic properties due to structural changes plays an important role, but nevertheless diffusion processes at the interfaces cannot be neglected. Annealing experiments of amorphous Alcoated GdTbFe-films of different thickness evaporated onto glass substrates are reported. The samples were annealed at temperatures T = 150, 250, and 350°C. The degradation of coercivity, Hc, torque hysteresis angle, 2α, saturation magnetization, Ms, and anisotropy constant, Ku, was measured at room temperature after the annealing times t = 10.2ⁿ(n = 0...9) minutes. The experiments show that all magnetic properties degrade linearly in a logarithmic scale of annealing time. The aging dynamics depends on the thickness of the MO-film. Kuand Msare only affected by surface induced effects. SIMS profiles show the diffusion of oxygen from the interfaces resulting in an increase of Msand a decrease of Kuto even negative values. Hcand 2α decrease due to surface and bulk induced effects. The experimental data imply that only Hcand 2α are changing due to bulk effects whereas Kuremains constant.