Effect of spacer material on the magnetic surface anisotropy in ultrathin Fe₇₀B₃₀ multilayer films Available to Purchase

It has been found recently that the magnetic surface anisotropy K_s in Fe₇₀B₃₀/Ag multilayer films decreases monotonically with magnetic layer thickness (2L) for 2L<16.5 Å. In order to determine possible effects of the spacer material on the surface anisotropy in the aforementioned system, Ag has been replaced with Al₂O₃ and ferromagnetic resonance (FMR) measurements have been made on these films. These Fe₇₀B₃₀/Al₂O₃ films were fabricated by magnetron sputtering and were characterized by x‐ray‐diffraction and vibrating sample magnetometer (VSM) measurements in addition to FMR. In the region where K_s depends upon 2L, the data is insufficient to confirm the thickness dependence of K_s that was observed in Fe₇₀B₃₀/Ag, while in the region where K_s is independent of 2L, the values of K_s deduced for Fe₇₀B₃₀/Ag and Fe₇₀B₃₀/Al₂O₃ are in good agreement. The latter is particularly interesting in light of the enormous difference in conductivity between Ag and Al₂O₃.