Giant Asymmetry of Domain Walls Propagation in Pd/Co/Pd(111) Epitaxial Structures with Different Interface Roughness

The motion of domain walls (DWs) in magnetic nanoscale layered systems attracts a great deal of attention due to the possible chiral nature of the energy dissipation occurring because of the presence of strong spin-orbit coupling and the broken inversion symmetry. Here, we report on a giant asymmetry of DWs propagation in the creep regime in the Pd/Co/Pd epitaxial system under the influence of driving out-of-plane (OOP) and symmetry breaking in-plane (IP) magnetic fields. With an increase in the thickness of the bottom Pd layer, which in turn leads to growth of the interface roughness of the Pd/Co/Pd samples, the asymmetry of DWs propagation increases. The maximal reliably measured relation of the velocities of right-handed and left-handed propagating DWs in the Pd(12.5)/Co(0.7)/Pd(3) sample, where thickness is in nanometers, is equal to 6600, which means almost complete blocking of the propagation of DWs in the direction determined by the appropriate choice of a combination of the applied magnetic fields. The observed giant asymmetry of the propagation of DWs indicates the importance of nanoengineering the parameters of the interfaces to control the propagation of DWs in magnetic memory and logic devices.