Speaker
Description
Magnetic skyrmions are tiny whirls of magnetization, in which the magnetization vector locally reverses its preferred orientation and whose stability is due to a delicate balance of forces acting at nanoscale. In this talk, I will discuss the situation in which these magnetization states take the shape of skyrmionic bubbles in ultrathin ferromagnetic films, whereby the skyrmion consists of a compact region of magnetization opposite to the magnetization in the bulk of the film, with a narrow transition layer in the form of a chiral domain wall. Starting with the reduced two-dimensional micromagnetic energy, I will derive the energy of these bubbles via Gamma-convergence in finite samples of increasing size, resulting in a geometric variational problem describing the shape of skyrmionic bubbles in the presence of an applied magnetic field. I will finally touch upon radially symmetric bubbles as the DMI strength approaches critical. This is joint work with M. Piccinini, M. Novaga and V. Slastikov.