Correlated magnetic vortex chains in mesoscopic cobalt dot arrays

Nucleation and annihilation of vortex states in two-dimensional arrays of densely packed cobalt dots were studied using magnetic force microscopy (MFM) imaging. A signature of dipolar interactions between single-domain state dots and vortex state dots was observed from the dependence of vortex nucleation and annihilation fields on interdot separation. The results show that the mechanism of vortex nucleation/annihilation in arrays of densely packed cobalt dots is influenced by the magnetostatic coupling between the dots.