Enhancement of spin orbit torques in a Tb-Co alloy magnetic wire by controlling its Tb composition

We investigated the current-induced domain wall motion (CIDWM) in Pt(3 nm)/TbxCo1-x(6 nm) alloy wires with various Tb composition (x). We found that the threshold current density (Jth) for the CIDWM in the TbxCo1-x alloy wires decreases with increasing x. In particular, the Jth with x = 0.37 is almost 3 times smaller than that with x = 0.23. We estimated Dzyaloshinskii-Moriya interaction (DMI) effective field (HDMI) by measuring CIDWM in a longitudinal magnetic field. We found that DMI constant (D) estimated by the HDMI also strongly depends on x. The size of the DMI may be modified by changing electronegativity or local atomic arrangement in Tb-Co alloy. These results suggest that Tb can induce strong HDMI and effectively affect CIDWM in TbxCo1-x alloy wires.