Effect of Temperature on the Ferromagnetic-Resonance Field and Line Width of Epitaxial Fe Thin Films

The temperature dependence of the ferromagnetic-resonance field (H_res) and line width (DeltaH) of epitaxial Fe thin films were studied. It is observed that H_res increases whereas DeltaH decreases with the increase in temperature. The change in H_res is governed by the temperature dependence of the saturation magnetization and the magneto-crystalline anisotropy energy of the film. The present low-temperature investigations of H_res obeys the well-known T^3/2 Bloch law. The resonance line width as a function of temperature shows a transition temperature (T₁) separating two different regimes. This behavior may be associated with the temperature dependence of the anistropy. The H_res results are confirmed theoretically by simulating the power absorbed at ferromagnetic resonance by using the Landau-Lifsthiz-Gilbert equation.