Magnetic dot clusters for application in magneto-electronics

Electron beam lithography has been exploited to prepare arrays of elliptical dots of thickness 40 nm and lateral size 700 300 nm. Arrays of both isolated elements and squared clusters of dots were prepared. The hysteresis cycles of these arrays were measured by magneto-optical Kerr effect. Micromagnetic simulations permitted us to reproduce the magnetization curves and to interpret the magnetization reversal mechanism. This proceeds through the formation of two vortexes, due to the rather large dimensions of the dots. Evidence is given to the influence of inter-dot dipolar coupling within the cluster.