Micromagnetics of derivative ring-shaped nanomagnets

We present a systematic investigation of the magnetization reversal process in derivative ring-shaped nanomagnets. As the transition from onion to vortex state in magnetic rings is through the displacement of the domain wall along the circumference of the ring, we have investigated the effect of removing different segments of the ring structure on the magnetization reversal processes. We observed that the magnetic spin configuration is strongly influenced by the axis that is removed, as confirmed by the magnetic force microscopy studies. Our understanding of the reversal process was aided using micromagnetic simulations, which are in very good agreement with experimental results.