Article ID: M2016106
A series of 40 nm-thick Fe100−xSix (x = 0, 6 or 10 at%) single-crystal films with an A2 phase were fabricated on MgO(001) substrates. Variations in the ferromagnetic resonant field (Hr) and linewidth (ΔH) values with changes in the azimuthal angle (ϕH) were subsequently evaluated, using an electron cyclotron resonant system with X-band (9.86 GHz) microwaves at room temperature. The Hr values exhibited fourfold symmetric behavior while varying the ϕH. In addition, the ΔH values demonstrated symmetric behavior, with intense peaks in the vicinity of the magnetization hard-axis, and so the ΔH variation was reduced with increasing Si content. An analysis of the data was performed, employing the magnetization coherent rotation model. It was determined that the appearance of strong peaks can be attributed to differences between ϕH and the magnetization angle (ϕM), based on the term [cos(ϕH − ϕM)]−1. This is believed to result from the insufficient Hr strength obtained during measurements with X-band microwaves relative to the anisotropy fields of the films.