Excitation and Propagation of Spin Waves with Orbital Angular Momentum in Ferromagnetic Nano-Cylinder

Abstract

When the magnetic moment lined order in the magnetic materials generates collective movement, we call this phenomenon as spin wave. The spin wave that not only has momentum but also has orbital angular momentum in the propagation process is called twisted spin wave. Different from the plane wave, twisted spin wave will twist alone the central axis during its propagating. Finally, the twisted spin wave will distribute in spiral way, meanwhile the spin wave always possesses angular momentum. This paper studies eigenmodes of twisted spin waves in ferromagnetic nanocylinder; through applying a sinc pulse magnetic field in the bottom of the nanocylinder and using FFT, analyzes the component of dynamic magnetic moment; and gets the resonant spectrum of twisted spin waves. Then we use inverse Fast Fourier Transform to acquire the mode of twisted spin wave with l = 1. Moreover, by applying an in-plane rotating field, a twisted spin wave with topological charge l = 1 can be excited.