Magnetization Reversal in a Double-Walled Infinite Nanotube

The nucleation fields of magnetization reversal is calculated here for an infinite, hollow nanotube formed by two ferromagnetic walls. The two tubes can reverse either by curling or by rotation in unison, and have thus four separate reversal modes. The properties of the reversal fields are summarized by means of a series of phase diagrams which display the dependence of the reversal mode on the inner and outer radius of the nanotube. Under certain conditions a large range of nucleation fields my be achieved by a small variation of the nanotube radius.