What are magnons?

Magnons are collective excitations in magnetically ordered systems.

For the sake of simplicity, the movie illustrates a one-dimensional chain of magnetic moments in a ferromagnetic material. In equilibrium, all magnetic moments in such a ferromagnet point in the same direction.

If one of these magnetic moments is pushed out of equilibrium, like by some external magnetic field, it does not directly go back but rather precesses around the equilibrium direction. This precession of one magnetic moment then influences its neighboring magnetic moment which starts to precess as well but with a slightly different phase, i.e., it drags behind the first magnetic moment. This precessing motion then propagates along the chain of magnetic moments like a wave, which is called a magnon.

What is a magnetic vortex?

In thin magnetic films, a magnetic vortex describes a non-uniform magnetization state in which the magnetic moments curl around the vortex core, a region where the magnetization points out of the plane. In nano- to micro-meter sized magnetic disks, magnetic vortices occur naturally to avoid surface charges from magnetic moments pointing out of the disk.

The sense of magnetization rotation determines the vortex chirality, the direction of the vortex core defines its polarity.