Giant bulk spin-orbit torque and efficient electrical switching in single ferrimagnetic FeTb layers with strong perpendicular magnetic anisotropy

Efficient manipulation of antiferromagnetically coupled materials that are integration-friendly and have strong perpendicular magnetic anisotropy (PMA) is of great interest for low-power, fast, dense magnetic storage and computing. Here, we report a distinct, giant bulk damping-like spin-orbit torque in strong-PMA ferrimagnetic Fe100-xTbx single layers that are integration-friendly (composition-uniform, amorphous, and sputter-deposited). For sufficiently thick layers, this bulk torque is constant in the efficiency per unit layer thickness, xi(j)(DL)/t, with a record-high value of 0.036 +/- 0.008 nm(-1), and the damping-like torque efficiency xi(j)(DL) achieves very large values for thick layers, up to 300% for 90 nm layers. This giant bulk torque by itself switches tens of nm thick Fe100-xTbx layers that have very strong PMA and high coercivity at current densities as low as a few MA/cm(2). Surprisingly, for a given layer thickness, xi(j)(DL) shows strong composition dependence and becomes negative for composition where the total angular momentum is oriented parallel to the magnetization rather than antiparallel. Our findings of giant bulk spin torque efficiency and intriguing torque-compensation correlation will stimulate study of such unique spin-orbit phenomena in a variety of ferrimagnetic hosts. This work paves a promising avenue for developing ultralow-power, fast, dense ferrimagnetic storage and computing devices.& nbsp;& nbsp;Published under an exclusive license by AIP Publishing.

Automated summary

This study reports a distinct and giant bulk damping-like spin-orbit torque in strong-perpendicular magnetic anisotropy (PMA) ferrimagnetic Fe100-xTbx single layers. The giant bulk torque can switch thick Fe100-xTbx layers with very strong PMA and high coercivity at low current densities.