Sommaire:

Skyrmions are topologically stable excitations that appear in magnetic systems, as non-trivial spin textures typically composed of tens of spins. In chiral magnetic systems, skyrmions are stabilized by the antisymmetric Dzyaloshinskii–Moriya (DM) interaction. Recent experimental studies observed the magnetic skyrmions in chiral magnets with the DM interaction like MnSi and FeGe. In three-dimensional bulk systems of chiral magnets, skyrmions are thermodynamically stable in a tiny window of the phase diagram only as a triangular crystal state. In contrast to the three-dimensional case, even isolated skyrmions are also stable in two dimensions, and a melting transition from an ordered phase to a liquid phase of skyrmions occurs at finite temperature.
In this seminar, we present numerical results on the melting transition in a two-dimensional classical Heisenberg model of a chiral magnet. By mapping skyrmions to two-dimensional point particles, we compute the orientational and the positional orders of skyrmions. We discuss our results from the viewpoint of the Kosterlitz-Thouless-Halperin-Nelson-Young theory of two-dimensional melting of particles.

Pour plus d'informations, merci de contacter Sorichetti V.