Influence of grain boundaries on the magnetization reorientation transition in ultrathin films

A magnetic reorientation transition is studied in situ in model experimental systems of Co grown on Au(111) and Au(788). Results from magneto-optic measurements and scanning tunneling microscopy, obtained on these two different self-ordered systems, demonstrate that grain boundaries formed during the film growth strongly influence the magnetic properties of the films. The nanometer scale of the magnetization reversal at the transition makes the temperature an essential parameter to predict experimental features observed in the magnetic reorientation transition.