Fig. S6.

Spin texture evolution with magnetic field at 170 K in FeGe nanodisk with a diameter of 270 nm (A) and 330 nm (B). Helical spin texture gradually evolves to skyrmions with the increase of external magnetic field. The three (or four) skyrmions in the 270-nm (or 330-nm) nanodisk that were nucleated from the edge shift to the center of the disk with further increasing of H. The skyrmion number appears to be equal to that of the helix period. Skyrmions annihilated one by one under increasing magnetic field from 3.29 kOe to 3.44 kOe. The white dashed circles indicate the interface of FeGe and amorphous PtC_x, and the color wheel in the last panel indicates the direction and strength of magnetization.