Mapping metastable magnetic textures in ( Fe 0.5 Co 0.5 ) 5 GeTe 2 with in situ Lorentz transmission electron microscopy

Topologically protected magnetic textures are a promising route to low-energy control of magnetism, but they are most often studied away from ambient conditions, typically at low temperatures and high magnetic fields. Here we use Lorentz transmission electron microscopy with control of temperature and magnetic field to investigate the skyrmion metastability in ( Fe 0.5 Co 0.5 ) 5 GeTe 2 (FCGT). By field-cooling FCGT in magnetic fields of different magnitude to different base temperatures and then removing the applied field, we create meta(stable) zero-field magnetic states. We use this method to build a phase diagram of the zero-field metastable spin structures in FCGT, which will be critical for selecting the desired topologically protected spin state for future studies to manipulate magnetism with stimuli such as electric current, electric field, mechanical strain, and more.