Strain engineering of magnetic proximity effect and spin-orbit torque in heavy metal/ferromagnet heterostructures

Spin-orbit torque (SOT) has been proposed as an efficient mechanism to switch the magnetization in heavy metal/ferromagnet heterostructures. Several experiments show controversial results on the relationship between the magnetic proximity effect (MPE) and the SOT efficiency in heavy metal/ferromagnet structures. In this work, we use first-principles calculations to investigate the dependence of the MPE and the SOT efficiency on the Pt/CoFe interfacial strain in a model structure of Pt/ CoFe/MgO. We have found that the interfacial strain can effectively reduce electron hybridization between Pt and CoFe and thereby significantly suppress the MPE while enhance the SOT efficiency. Thermodynamic magnetics analysis further confirmed these findings. Our results have pointed out a new research direction in which one uses interfacial strain as an effective route to design efficient spintronic devices.