Demagnetizing field effect on the magnetization reversal process of cobalt nanomagnets

The demagnetizing field effect of the magnetization reversal of large area Co nanodot arrays with diameter of 125 nm and interdot spacing of 175 nm was analyzed in this research. The magnetic properties of the nanomagnetic dots fabricated using deep UV lithography and electron beam evaporation were investigated using vibrating sample magnetometer (VSM). It was observed from the hysteresis loops that the magnetostatic energy from individual dots is much greater than the intrinsic magnetic anisotropy of the bulk Co film. Also, when the applied field decrease from saturation to zero, the nanodots tend to form the flux closure configuration but the directions of cores were random. A monotonic variation of nucleation and annihilation fields with Co thickness was also observed.