Thickness dependence of magnetic surface anisotropy in ultrathin amorphous films (abstract) Available to Purchase

In searching for a possible dependence of magnetic surface anisotropy on film thickness, the magnetic surface anisotropy constant K_s of compositionally modulated amorphous Fe₇₀B₃₀‐Ag films¹ was measured by means of a method² involving the dependence of the ferromagnetic resonance (FMR) fields on the magnetic layer thickness 2L. The ratio of the Ag to the Fe₇₀B₃₀ thickness was 3 to 1 while 2L ranged from 1.6 to 90 Å. Measurements were made with the applied static magnetic field parallel and perpendicular to the plane of the sample, at both X‐ and K‐band frequencies for at least 14 values of 2L in each case. The results of magnetization measurements, made by SQUID magnetometry, have already been reported.¹ Using the measured values of the thin‐film magnetization and the aforementioned method, the value of K_s has been determined over the entire range of 2L. The results are consistent with a constant value of K_s for 2L>16.5 Å, while K_s is found to decrease monotonically as 2L is reduced from 16.5 to 1.6 Å. A similar decrease of K_s is found even if the bulk value rather than the thin‐film values of the magnetization is used throughout. In addition, the value of K_s has been deduced for 2L=4.1, 6.7, 10.2, and 16.7 Å, from the original SQUID data. These values are in good agreement with those determined by the FMR method.