Spin-wave propagation and spin-polarized electron transport in single-crystal iron films

The techniques of propagating spin-wave spectroscopy and current-induced spin-wave Doppler shift are applied to a 20-nm-thick Fe/MgO(001) film. The magnetic parameters extracted from the position of the spin-wave resonance peaks are very close to those tabulated for bulk iron. From the zero-current propagating wave forms, a group velocity of 4 km/s and an attenuation length of about 6 $\ensuremath{\mu}\mathrm{m}$ are extracted for 1.6-$\ensuremath{\mu}\mathrm{m}$-wavelength spin wave at 18 GHz. From the measured current-induced spin-wave Doppler shift, we extract a surprisingly high degree of spin polarization of the current of $83%$, which constitutes the main finding of this work. This set of results makes single-crystalline iron a promising candidate for building devices utilizing high-frequency spin waves and spin-polarized currents.