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Controlling the motion of magnetic domain walls (DWs) in ultrathin films with perpendicular magnetic anisotropy (PMA) has opened perspectives for mass-storage applications such as “racetrack memory”. However, a crucial issue for this technology is to efficiently move and store domain walls along very narrow wires. Jointly with Micron Semiconductor, Singulus Technologies, and the Center for Nanoscience and Nanotechnology (C2N) at Université Paris Sud-CNRS, researchers at IMM Unit of Agrate Brianza 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, a very efficient domain-wall motion along the 70 nm conducts separating the steps is demonstrated. The presented approach is compatible with nanoscale devices and large-scale mass production, opening new opportunities for domain-wall storage applications.

This study is published in Physical Review Applied, December 2018

Corresponding author @IMM: Roberto Mantovan