Reduction of intrinsic critical current density for current-induced domain wall motion by using a ferrimagnetic nanowire with perpendicular magnetic anisotropy

We herein discuss the use of a ferrimagnetic nanowire for current-induced domain wall motion in order to satisfy both high perpendicular anisotropy and low saturation magnetization. We demonstrate the current-induced domain wall motion in magnetic nanowires with various saturation magnetizations by using micromagnetic and analytical calculations. The intrinsic critical current velocity was reduced with decrease of saturation magnetization even if the domain wall width was almost constant, and the intrinsic critical current velocity also can be reduced with the optimum wire width. A significant reduction of critical current density can be obtained by decreasing the saturation magnetization even if the spin polarization of ferrimagnetic materials is below 0.1 because the decrease in the hard-axis anisotropy is dominant for current-induced wall motion.