ABSTRACT
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235
8 .1 Topological Definition of a Skyrmion By definition, a vector field is called a skyrmion or said to be skyrmionic if it has a spherical topology. In the following, we will explain the concept of topology, illustrate how the mathematical definition is applied to a magnetic spin configuration, and discuss the implications of a spin structure being a skyrmion.
