Engineering Domain-Wall Motion in Co-Fe- B/Mg O Ultrathin Films with Perpendicular Anisotropy Using Patterned Substrates with Subnanometer Step Modulation

Control of magnetic domain-wall motion in nanowires has attracted great interest due to the possibility to develop nonvolatile memory and logic circuits. We show that efficient domain-wall pinning can be engineered by growing Co-Fe-B/MgO ultra-thin magnetic films with perpendicular anisotropy on a patterned substrate exhibiting subnanometer steps modulation. The ratio of domain-wall velocity along and across the steps is found to be as high as 70, which corresponds to a variation of the depinning field up to 7 mT demonstrating a very efficient storing pinning scheme. In addition, we demonstrate very efficient domain-wall motion along the 70 nm conducts separating the steps. Our approach is compatible with nanoscale devices and large-scale mass production, opening new opportunities for domain-wall storage applications.