The control of magnetic vortex state in rectangular nanomagnet

We study the magnetic vortex states in rectangular nanomagnet with aspect ratio close to two by micro-magnetic simulations and experiments comparatively, and propose a simple way to manipulate both the chirality and polarity independently by tuning the direction of the in-plane magnetic field. There are always two vortices which have opposite chirality with Neel type wall and identical polarity for the rectangular nanomagnet with aspect ratio close to two. Four stable vortex states can be genetated from the uniformly magnetized state by in-plane magnetic field, and specific vortex states depend on the direction of the initial magnetization. The phenomenont of the formation of vortex states was explained based on the vortex dynamics. Also the reliability of proposed method was confirmed by domain structure using magnetic force microscopy (MFM) in experiment.