  We present a detailed study of the phase diagram surrounding the skyrmion
lattice (SkL) phase of Cu2OSe2O3 using high-precision magnetic ac
susceptibility measurements. An extensive investigation of transition dynamics
around the SkL phase using the imaginary component of the susceptibility
revealed that at the conical-to-SkL transition a broad dissipation region
exists with a complex frequency dependence. The analysis of the observed
behavior within the SkL phase indicates a distribution of relaxation times
intrinsically related to SkL. At the SkL-to-paramagnet transition a narrow
first-order peak is found that exhibits a strong frequency and magnetic field
dependence. Surprisingly, very similar dependence has been discovered for the
first-order transition below the SkL phase, i.e. where the system enters the
helical and conical state(s), indicating similar processes across the
order-disorder transition.
