Propagation of a magnetic domain wall in the presence of AFM fabricated defects

We can control the magnetization reversal process in Pt/Co/Pt ultra thin fi lm devices by using mesoscopic defects fabricated by atomic force microscop e (AFM) lithography. Holes and grooves locally cutting the Co layer are wri tten by direct mechanical indentation of the metal samples by the AFM tip. The smallest lateral feature size of these artificial structures (down to 2 0 nm for a hole) is comparable to the intrinsic Barkhausen length (similar to 25 mn) of the films. The influence of the AFM fabricated structures on t he magnetization reversal process in micron sized devices was studied by Ke rr microscopy and extraordinary Hall effect measurements. Single point defe cts act as mesosocopic domain wall pinning centers, while lines effectively block the domain wall propagation. Study of the influence of well characte rized defects should help understand better the magnetization reversal proc esses in our films.