Exchange stiffness in the Co2FeSi Heusler compound

Using Brillouin light scattering spectroscopy, we determine the spin-wave exchange stiffness D and the exchange constant A for thin films of the full Heusler compound Co2FeSi prepared by pulsed laser deposition. The thermal spin-wave spectra were measured in various magnetic fields, for different transferred spin-wave momenta, and for different film thicknesses. Fitting the observed spin-wave frequencies, we find an extraordinarily large value of D = 7.15 ± 0.20 meV nm2 (A = 31.5 ± 1.0 pJ m-1) which is, to the best of our knowledge, only surpassed by the intermetallic compound Fe53Co47 (Liu et al 1994 J. Appl. Phys. 75 7021). (fast track communication)