Model for domain wall pinning by randomly distributed nanosized defects in ultrathin magnetic films

In this paper we calculate the pinning field associated with domain wall motion in ultrathin magnetic films, which is controlled by a high density, n, of weak defects. The pinning field is shown to vary as n5/6d-1/2, d being the thickness of the magnetic layer. This model is applied to a Au/Co/Au ultrathin film structure with perpendicular anisotropy, close to the spin reorientation transition.