Tuning Slonczewski-like torque and Dzyaloshinskii–Moriya interaction by inserting a Pt spacer layer in Ta/CoFeB/MgO structures

Slonczewski-like torque and the Dzyaloshinskii–Moriya interaction (DMI) are important factors in current-induced magnetization switching and domain-wall motion seen in ferromagnetic metal (FM)/heavy metal (HM) structures. We demonstrate the tuning of both factors by inserting a thin Pt layer between Ta and CoFeB in the Ta/CoFeB/MgO structures. The results suggest that the Slonczewski-like torque and DMI decreases with increasing Pt thickness (tPt) in the range 0–1 nm. In consequence, the critical switching current density from the induced spin-orbit torque (SOT) increases whereas the required in-plane field for deterministic switching decreases. The sign of the DMI reverses around tPt = 1 nm, confirming that D has the opposite sign at the Ta/CoFeB and Pt/CoFeB interfaces; but its intensity saturates at tPt = 3 nm, suggesting that several interface monolayers may contribute to the DMI. Our results verifies that a thin HM interlayer may be a suitable route to tailor the SOTs and DMI at the HM/FM interface, as well as the current-induced magnetization switching in these structures.