NANOSCALE MAGNETIC DOMAINS IN MESOSCOPIC MAGNETS

The basic magnetic properties of three-dimensional nanostructured mate rials can be drastically different from those of a continuous film. Hi gh-resolution magnetic force microscopy studies of magnetic submicrome ter-sized cobalt dots with geometrical dimensions comparable to the wi dth of magnetic domains reveal a variety of intricate domain patterns controlled by the details of the dot geometry. By changing the thickne ss of the dots, the width of the geometrically constrained magnetic do mains can be tuned. Concentric rings and spirals with vortex configura tions have been stabilized, with particular incidence in the magnetiza tion reversal process as observed in the ensemble-averaged hysteresis loops.