Field-free Switching of Perpendicular Magnetization Induced by Inversion Symmetry Breaking at the Heavy-metal/Merromagnet Interface
In this paper,the influence of the out-of-plane field-like torque induced by the interfacial inversion symmetry breaking in the heavy-metal/ferromagnet(the L11 phase CuPt/CoPt)bilayer on the characteristics of field-free perpendicular magnetization switching in the ferromagnetic layer is studied based on the macro-spin model.It is demonstrated that in the L11 phase CuPt/CoPt bi-layer with the inversion symmetry breaking,though the induced out-of-plane field-like torque,namely,the 3 m torque is quenched in the x-y plane,the field-free perpendicular magnetization switching can also be observed through the unsteady oscillating effect of the magnetization between above the x-y plane and below the one,when an appropriate short pulsed electric current is to be applied along the high symmetry axis of the heavy metal layer.Moreover,when the induced out-of-plane field-like torque is large enough,it can increase the selection range of short pulsed current length and further reduce the threshold current density of the steady magneti-zation switching.These results suggest an alternative theoretical scheme for the realization of field-free perpendicular magnetization switching of spin-orbit torque-magnetic random access memory.
macro-spin modelspin-orbit torquemagnetic random access memory
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