Fig. 3: Variation in the magnetic state at room temperature at different magnetic fields after FC manipulation.

a–c Representative underfocused LTEM images of skyrmion bubbles taken at 93 K after a field cooling manipulation. Micromagnetic simulations of the domain field cooling process as a function of magnetic fields of 100 Oe (d), 400 Oe (e), and 800 Oe (f). g Magnetic field-dependent mean size and density of skyrmion bubbles obtained from LTEM data. h The calculated mean size and density of skyrmions under different magnetic fields. i Field dependence of the energy terms in the simulation after a field cooling process.