Measuring the formation energy barrier of skyrmions in zinc-substituted Cu2OSeO3

Abstract

We report small-angle neutron scattering (SANS) measurements of the skyrmion lattice in ${({\mathrm{Cu}}_{0.976}{\mathrm{Zn}}_{0.024})}_{2}{\mathrm{OSeO}}_{3}$ under the application of electric and magnetic fields. These measurements show an expansion of the skyrmion lattice stability region with electric field. Furthermore, using time-resolved SANS, we observe the slow formation of skyrmions after an electric or magnetic field is applied, which has not been observed in pristine ${\mathrm{Cu}}_{2}{\mathrm{OSeO}}_{3}$ crystals. The measured formation times are dramatically longer than the corresponding skyrmion annihilation times after the external field is removed, and increase exponentially from 100 s at 52.5 K to 10 000 s at 51.5 K. This thermally activated behavior indicates an energy barrier for skyrmion formation of 1.57(2) eV, the size of which demonstrates the huge cost for creating these complex chiral objects.