Abstract
We study the magnetic domain pattern in a ferrimagnetic CoTb thin film using Lorentz transmission electron microscopy. The evolution of domain patterns is captured at different temperatures and external fields. Magnetic dipole skyrmions and bubbles can be created simultaneously by increasing the temperature of the sample and applying appropriate out-of-plane magnetic fields. By tuning the external magnetic fields, it is found that the skyrmions are annihilated at a higher magnetic field compared to bubbles. Moreover, we also find that the in-plane magnetic field influences the formation and the shape of skyrmions and bubbles. Further, micromagnetic simulations are also consistent with the experimental observations. Our findings provide insights into the magnetic field stability of skyrmions.