A spin-wave Doppler technique is used to measure the spin-transfer velocity and the current polarization in current-carrying (Ni80Fe20)1-xGdx alloy wires. Reduced magnetization values with Gd doping suggest possible increases in the spin-transfer velocity. Contrary to these expectations, we measured a decrease in the spin-transfer velocity upon introducing Gd dopants. For a current density of 1011 A/m2, the measured velocities range from 6.0 ± 0.6 m/s for pure Permalloy to 2.6 ± 0.3 m/s for (Ni80Fe20)94.5Gd5.5. Interpretation of these values yields a current polarization ranging from .71 ± .02 to .30 ± .01 for the same compositions. These results reveal that Gd dopants in Permalloy have a more significant impact on the current polarization than on the materials magnetization for these alloy compositions.
Citation: Journal of Applied Physics
Pub Type: Journals
nanomagnetics, spin, future electronics, spin waves, magnetism