Determination of the exchange constant of Tb0.3Dy0.7Fe2 by broadband ferromagnetic resonance spectroscopy

摘要

We present measurements of the exchange stiffness D and the exchange constant A of a sputtered 80 nm Tb0.3Dy0.7Fe2 film. Using a broadband ferromagnetic resonance setup in a wide frequency range from 10 GHz to 50 GHz, multiple perpendicular standing spin-wave resonances were observed with the external static magnetic field applied in–plane. The field corresponding to the strongest resonance peak at each frequency is used to determine the effective magnetization, the g–factor and the Gilbert damping. Furthermore, the dependence of spin-wave mode on field-position is observed for several frequencies. The analysis of spin-wave resonance spectra at multiple frequencies allows precise determination of the exchange stiffness D = (2.79 ± 0.02) × 10⁻¹⁷ T · m² for an 80 nm thick film. From this value, we calculated the exchange constant A = (9.1 ± 0.1) pJ · m⁻¹.