Enhanced magnetization drift velocity and current polarization in (CoFe)1-xGex alloys

A spin-wave Doppler technique is used to measure the drift velocity of the magnetization in current-carrying (CoFe)(1-x)Ge-x alloys. For a current density of 10(11) A/m(2), we obtain a large enhancement of drift velocity with increased Ge concentration from 3.1 +/- 0.2 m/s for CoFe to 8.2 +/- 0.6 m/s for (CoFe)(0.7)Ge-0.3. Interpretation of these values yields current polarization increasing from 0.84 +/- 0.04 to 0.95 +/- 0.05 as the Ge doping increases. While both spin-dependent conductivities decrease with increasing Ge concentration, the maximum in polarization is associated with a stronger relative change in the minority spin conductivity. (C) 2011 American Institute of Physics. [doi:10.1063/1.3554755]