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 $(CoFe)1−xGex$ alloys. For a current density of $1011A/m2$⁠, we obtain a large enhancement of drift velocity with increased Ge concentration from $3.1±0.2m/s$ for CoFe to $8.2±0.6m/s$ for $(CoFe)0.7Ge0.3$⁠. 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.