Tuning the size of skyrmion by strain at the Co/Pt 3 interfaces

Based on density functional theory calculations, we elucidated the tunability of the atomic structures and magnetic interactions of Co/Pt interface (one layer of hcp(0001) Co and three layers of fcc(111) Pt) and thus the skyrmion sizes using strain. The dispersion relations of the spin spiral in the opposite directions, E( ) and E(- ), were evaluated based on generalized Bloch equations. Effective exchange coupling (EC) and Dzyaloshinsky-Moriya interaction (DMI) parameters between different neighbors and at different lattice constants were derived by fitting the resulting spin spiral dispersion E( ) to EC model with DMI and E( )-E(- ) formula, respectively. We observed an increase in DMI and a significant decrease in EC with an increase in strain. Hence, the size of Néel-type skyrmions determined by the ratio of EC/DMI can be controlled by applying strain, leading to an effective approach to tailor the formation of skyrmion lattices by inducing slight structural modifications on the magnetic thin films.