Abstract
B doping effect on the spin orbital torque efficiency has been investigated in this work. The Ti (5nm)/ Pt (5nm, B doped)/ [Co (0.2nm)/ Ni (0.6nm)]2/ Ti (5nm) structures were prepared, and we directly doped B into Pt layer by co-sputtering and by inserting B dusting layer into Pt layer. Under the premise that the anisotropy field (H_k) and the saturation magnetization (M_s) of the Co/Ni multilayers are barely affected by the B doping, we analyze the spin orbital torque induced magnetic effective field by locking measurement. The results show that dusting layer can be more effective than the co-sputtering method in increasing the damping-like torque induced longitudinal effective field (〖ΔH〗_L), which may also due to different amount of the B dopants. Furthermore, by changing the dusting layer insert position in Pt and the dusting layer thickness, we found that setting the dusting layer at the middle of the Pt layer gain the largest 〖ΔH〗_L and it increase with the B dusting layer thickness, which can be 67% larger than the non-doped sample. Finally, we apply the magnetization switching test and realize that the critical switching current density also reduced with the increasing dusting layer thickness. It can be inferred that additional spin orbital torque can be induced by the B impurity in the Pt layer. Furthermore, we also clearly demonstrate that the critical current for magnetization switching can be reduced by setting the B dusting layer, which shows potential for improving performance of future spintronic devices .