Martin Speight (School of Mathematics, University of Leeds) – The ground state of a chiral ferromagnet

Joint work with Bernd Schroers (Edinburgh), Tom Winyard (Dundee)

Some thin ferromagnetic films can support topological defects in their magnetization vector called magnetic skyrmions, stabilized by a chiral phenomenon called the Dzyaloshinskii-Moriya (DM) interaction. These have been proposed as bits in next-generation data storage devices. In some circumstances, isolated skyrmions may have (in a meaningful sense) negative total energy. It's then favourable for the system to spawn infinitely many skyrmions which pack together into a periodic lattice. But this might not be the only negative energy configuration available to the system, so may or may not be its ground state.

I will present a careful analysis of a simple but rather general model of thin ferromagnets including a completely general DM interaction and the Zeeman energy of an arbitrary applied magnetic field. The aim is to understand the parameter domain on which the ground state of the system is a skyrmion lattice, and, in this case, what the unit cell of the lattice looks like.