Metal doping effects on the skyrmion Cu$_2$OSeO$_3$

There is a considerable research interest in skyrmion whose magnetic properties have a remarkable characteristic as a vortex-like spin orientation. Recently, neutron scattering and Lorentz transmission electron miscropy measurements showed that Cu$_{2}$OSeO$_{3}$ exists a skyrmion state. We have doped transition metals (Fe, Mn, V) in Cu$_{2}$OSeO$_{3}$ and measured dc magnetization and ac susceptibility by scaning magnetic field. The Fe and Mn doping effect on the A phase in T-H phase diagrams of Cu$_{2}$OSeO$_{3}$ has been studied. Interestingly, the doping with V is different from that with Fe and Mn. The physical significance for metal doping on the skyrmion Cu$_{2}$OSeO$_{3}$ will be discussed.