Magnetization dependent spin orbit torques generated by ferrimagnetic FeCoTb alloys

Spin-orbit torques (SOTs) generated by magnetic materials have prompted a surge of interest in low-power spintronics. In this context, rare-earth doped magnetic alloys are the ideal candidate due to the low symmetry and large spin-orbit coupling. Here, we present a study on SOTs generated by ferrimagnetic FeCoTb alloys in permalloy (Ni80Fe20, Py)/Cu/FeCoTb spin valve structures, showing high-efficient damping-like and field-like torques. Crucially, the spin Hall conductivity of FeCoTb is up to 6.32 × 105 (ℏ/2e) Ω−1m−1, larger than that in conventional heavy metals. By controlling the magnetic configuration of the spin valve structure, the magnetization dependent behavior of the SOTs is achieved, which may origin from the anomalous Hall effect of FeCoTb dominated by Tb magnetization. Our results demonstrate great prospects of ferrimagnetic materials for low-power spintronic applications.