Wave reversal mode: A new magnetization reversal mechanism in magnetic nanotubes

•We have performed micromagnetic simulations of Ni and Py nanotubes as a function of the external magnetic field.•A new striking reversal mechanism, which we have called wave reversal mode (W), has been identified.•This phenomenon describes unusual behaviors in nanotubes when the field is applied perpendicular to its axis.•A sharp increase in remanence is an unequivocal signal that the system reverses according to this mechanism. We have investigated the magnetic properties of 14 nm thick and 1 μm long nickel and permalloy nanotubes with external diameters of 40 and 100 nm as a function of the angle θ at which the external magnetic field is applied. Our results show that the coercivity of 40 nm diameter nickel nanotubes follows a non-monotonic behavior from θ = 0° up to θ = 60°, while that corresponding to permalloy displays an increasing monotonic trend at the same angular range. At θ = 90°, both materials evidence a sharp drop of the coercivity to zero, indicating that the reversal mechanism has changed to a pseudo-coherent rotation. On the other hand, nickel and permalloy nanotubes with 100 nm in diameter exhibit a similar angular dependence of the coercivity, reversing their magnetization through the nucleation and propagation of vortex domain walls for angles lower than 75°. For θ = 90°, a novel striking mechanism, the wave reversal mode (W), arises. This phenomenon leads to an unusual S-type shape in the hysteresis curves at those given parameters, which is until now an effect that has not been reported for these nanostructures.