Generation of Spin Currents in the Skyrmion Phase of a Helimagnetic Insulator $mathrm{Cu_2OSeO_3}$

We report spin-current generation related with skyrmion dynamics resonantly excited by a microwave in a helimagnetic insulator $mathrm{Cu_2OSeO_3}$. A Pt layer was fabricated on $mathrm{Cu_2OSeO_3}$ and voltage in the Pt layer was measured upon magnetic resonance of $mathrm{Cu_2OSeO_3}$ to electrically detect injected spin currents via the inverse spin Hall effect (ISHE) in Pt. We found that ISHE-induced electromotive forces appear in the skyrmion phase of $mathrm{Cu_2OSeO_3}$ as well as in the ferrimagnetic phase, which shows that magnetic skyrmions can contribute to the spin pumping effect.