title: Giant Skyrmions stabilized by dipole-dipole interactions in thin ferromagnetic films.
abstract: Motivated by a recent magnetization reversal experiment on a TbFeCo thin film, we study a topological excitation in the anisotropic nonlinear sigma model together with the Zeeman and magnetic dipole-dipole interactions. Dipole-dipole interactions turn a ferromagnet into a frustrated spin system, which allows a nontrivial spin texture such as a giant Skyrmion. We derive an analytic formula for the Skyrmion radius. The radius is controllable by the external magnetic field. It is intriguing that a Skyrmion may have already been observed as a magnetic domain. A salient feature is that a single Skyrmion can be created or destroyed experimentally. An analysis is made also on Skyrmions in chiral magnets.
authors.affiliation: Department of Applied Physics, University of Tokyo, Hongo 7-3-1, 113-8656, Japan.
authors.forename: Motohiko
authors.initials: M
authors.lastname: Ezawa