Domain-Wall Motion Driven by Laplace Pressure in Co−Fe−B/MgO Nanodots with Perpendicular Anisotropy

As the march toward a spintronic future continues apace, the authors find that surface tension plays a critical role in the dynamics of curved magnetic domain walls (DWs). Direct observation with a Kerr microscope reveals that the switching-field distribution shifts to $l\phantom{\rule{0}{0ex}}o\phantom{\rule{0}{0ex}}w\phantom{\rule{0}{0ex}}e\phantom{\rule{0}{0ex}}r$ values of magnetic field as the size of Co-Fe-B/MgO nanodots decreases---quite the opposite of previous results. In the framework of an elastic interface, this can be explained as Laplace pressure applied to DWs nucleated at the edges of the dots. These findings suggest a path toward scalable spintronic devices with lower switching energies, based on controlling the nucleation and pinning potential of DWs.