Skyrmions and antiskyrmions from current-induced boundary instabilities*

We study generation and dynamics of skyrmions and antiskyrmions using current-induced torques at edges of magnetic regions with DMI (Dzyaloshinskii-Moriya interaction). The generation of skyrmions and antiskyrmions can be interpreted as taking place in the presence of a Doppler-like shift associated with current which occurs for magnons localized at the edge. These localized modes are analyzed by using the Bogoliubov-de-Gennes Hamiltonian written for magnons. We confirm our theoretical predictions using micromagnetics simulations where we observe that a current pulse closes the magnon band gap, leading to instabilities in the magnetic texture at the edge. We observe that the closure of the magnon band gap effectively causes the system to form skyrmions or antiskyrmions, depending on the type of DMI present.